Sync Magazine Volume 1 Number 1

.

Jan/Feb1981

Volume 1 , Number 1

$2.50 (USA)
£1.20 (UK)

The magazine for Sinclair ZX80 users

Games for the ZX8
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•Acey Ducey
• Nicomacus
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•30 Prograin
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The magazine for Sinclair ZX80 users

i_jn

January/February 1981

Volume 1 , Number 1

2

4

8

12

13

13
14

16

18

19
20

Interview With Ciive Sinclair Aht

Past, present and future of Sinclair Research

Sinclair ZX80 Tebbutt

An in-depth review of the ZX80

Building a MicroAce McLaughlin

The times, they are a changing

Hurkle McLaughlin

Search for the beastie on a 1 x 1 grid

Converting F rom Other Basics Lubar

FOR-NEXT loops

Editorial Lubar

Dealing Out a Conversion Lubar

How we converted a program

Acey Ducey Lubar

The popular card game for the ZX80

Nicomacus Ahl& McLaughlin

An ancient "boomerang" puzzle

A Weekend With the ZX80 Singer

The SNYC Challenge Stein

Can you fit Hammurabi into the ZX80?

22

24
26
30

32

34

38

39
39
40
42
45
46

Random Graphics McGath

Diagrams and pictures on the ZX80

ZX80 Circuit Diagram and Specs

Crash Cursor— Origin Truman

Castle Doors Horton

Cyclops, dragons, witches and zombies

Draw a Picture Branch

Faces, dogs and flowers

Dollars & Cents, Pounds & Pence Gaunt

Handling decimal numbers on the ZX80

LED Load Monitor Bridges

A perfect load and read every time

New Peripherals for ZX80

30 Programs for the ZX80- A Review Lubar

Linsac's Game Packs— A Review Stein

Resources for ZX80 and MicroAce Staff

Sync Reader Survey

Glossary of Computer Terms Staff

Staff

Publisher/ Editor-in-Chief

Editorial Director

Managing Editor

Associate Editor

Secretary

Production Manager

Typesetter

Financial Coordinator

Bookkepper

Customer Service

Order Processing

Circulation

David II. Ahl

George Blank

Jonathan A. Stein

David Lubar

Elizabeth Magin

Laura McKenzie

Jean Ann Vokoun

William I . Baumann

Patricia Kenneth

Patricia Brown

Alan Kelly

Dorian Snipes

Joan Swihart

Suzanne Guppy

Frances Miskovich

Dorothy Staples

Index to Advertisers

Advertiser

Page

Computer Coin Games

23

Computer Music Record

29

Creative Computing

Cover 3

K. Macdonakl

19

La mo Lem

Cover 2

Linsac

7

Melbourne House

29

MicroAce

Cover 4

Sinclair

17

SYNC Magazine

44

SYNCT-Shirts

37

Volume 1, Number 1

SYNC is published bi-monthly by SYNC, 39 East
Hanover Ave., Morris Plains, NJ 07950,

Subscriptions in USA: 6 issues S10; 12 issues S18;
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Send subscription orders or change of address
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Controlled circulation pending at New Berlin,

Wisconsin.

Copyright 1981 by Creative Computing. All rights
reserved. Reproduction prohibited in any form.
Printed in USA.

Jan/Feb 1981

1

Interview with
Clive Sinclair

David Ahl

Clive Sinclair is the man behind the
first mass pocket calculator, the first
scientific calculator kit and, now, a mass-
market computer. I talked to Clive while
in London at the PC W show.

Ahl: How did you get started in the elec-
tronics business?

Sinclair: 1 started in 1962 when I first came
to Sinclair Radionics. We were in the kit
business with hi fi systems and pocket
calculators, (we made the first pocket
calculator which is on display in the
Museum of Modern Art in New York).
From there we went into digital watches
and TV sets and for a while we were linked
with a government body in the U.K. At this
point 1 left, as this arrangement did not
work out too well. I took the same people
with me and reformed the company as
Sinclair Research Ltd. and launched the
personal computer.

Ahl: Does Sinclair Radionics and its

products still exist?

Sinclair: Only as a legal entity, but it
doesn't trade.

Ahl: So effectively today your main pro-
duct is ZX80?

Sinclair: I hat's right, but it's not our main
research program. Our biggest research
development program is on flat screen

television.

Ahl: Have you shown that at all? Or proved

its capability

Sinclair: Yes we have. We are at the stage
where we have demonstrated it and will be
doing so again later this year. We have
pilot production and hope to shortly be at
the next stage.
Ahl: What type of technology is used?

Sinclair: It is a flat screen Cathode Rav
Tube.

Reprinted with permission from Creative
Computing, December 1980.

Ahl: Does it have electron guns?
Sinclair: It has a conventional electron
gun, but instead of the beam following a
straight path, it bends to a right angle and
it splits the screen.

Ahl: Is it monochrome or could it be color?

Sinclair: It is monochrome today, but
eventually it will be color. We will pursue
that.

Ahl: That sounds very interesting. Sharp
had shown one about two years ago which
provoked much interest in the electronics
community but nothing ever came of it.
Today it doesn't look like they are any
closer to a commercial product than two
years ago.

The philosophy of the
company is very clear-
to lead in technology.

Sinclair: What Sharp showed was an early
development model of vertical projection,
which, novel as it was, was a long way
from a commercial product. But that is not
the case with ours. Ours gives a picture
which is not simply as good as a con-
ventional Cathode Ray Tube, but it is
better, and all the snags have been ironed
out.

Ahl: Do you anticipate that the price of
this will be competitive with the existing
technology?

Sinclair: Absolutely. There is no way we
would introduce something which cost
more than existing technology. Not only
does this have more feature advantages,
it has price advantages over conventional
technology. But in order to achieve this
and because conventional tubes are made
in such vast numbers, the only way it can
be competitive is to have very large scale
production. That is why it will take quite
some time before the tube emerges.

Ahl: About the ZX80; how long has that
been in development?
Sinclair: It started in March 1979 and it
was put on the market in February 1980.
Ahl: How many people were involved? It
seems to be quite a breakthrough on
many fronts. Did you have simultaneous
projects going on to bring it to fruition? Or
was it mainly you, or a small team of
people?

Sinclair: There were very few people in-
volved really. 1 had the original idea and
some of the system ideas. Then there were
about two or three engineers who were in-
volved in the detail and design; one
engineer in particular did the final design
and one wrote the software.

Ahl: Some people look at it and conclude
that it is no more than a larger computer
scaled down to smaller dimensions, while
others will look at it and think of it as one
of those language translators with a little
more capability. From glancing at the
specifications and seeing it at the Con-
sumer Electronics Show, I have the im-
pression that it has much more capability
than that and that it does not seem to be
just a scaled down computer. What is your
concept? How do you view the machine?

Sinclair: While the ZX80 is a true com-
puter in every sense, without any inherent
limitations, it obviously was restricted in
performance in its minimum configura-
tion. We wanted to sell at as low a price
as we possibly could, a computer upon
which people could start to learn, really
seriously, how to break into computers
and how to really learn what computers
were about. Now that might be an end in
itself for many of them, but these may be
executives who want to understand com-
puting so when they buy computers for
their firms or talk to people about the use
of computers in their firms, they do so
from a knowledgeable standpoint and they
don't feel awed by it. Equally, we see it as a
very powerful aid for students wanting to

SYNC Magazine

learn computing. But at the same time it is
expandable. We have just announced a
Basic for it — which is more of a pro-
fessional Basic than the original one and a
16K byte RAM pack for it at a very keen
price, (around $100), so that it can be taken
from the basic configuration to a really
very powerful system at a very low cost.
Hence our price will be somewhere
around half the conventional competi-
tions. I would make the point that in order
to do this we have done everything in-
house, i.e., in the way of anything having
to be specially done we had to write our
own Basic because we wanted to achieve
performance in the Basic as it wasn't
available on the existing Basics.

Ahl: Is that Basic compatible with Micro-
soft Basic or some other Basic on the
market or has it got a lot of bells and
whistles that make it incompatible with
others?

Sinclair: It is not compatible. It is our
own. We had to take that step in order to
achieve the bells and whistles that you

mentioned and have those features that
we feel are important to our customers. In
order to hit our cost goal we had to do a
better packing job than had been done be-
fore. The ROM in our basic machine is
just 4K bytes which contains everything —
Basic, operating system, keyboard control
and display I/O. Now there is no way we
could have done all that with an off-the-
shelf Basic. Furthermore, we then pack
data into the RAM at least four times as
tightly as anyone else. We would not have
been able to do that unless we had
our own Basic. Another thing that we
wanted was keyword entries. You may
have noticed that by pressing a certain
key a keyword is entered. So there is very
little for a non-typist to do. A lot of people
are put off in the learning stages with
having to type PRINT every time and
abbreviations can be misleading. We felt
this was very crucial and it is not in-
cluded in standard Basics, so we had to
choose to go away from the existing pat-
terns.

Ahl: Pertaining to the marketing of the
ZX80, do you anticipate selling it through
computer stores, department stores, or
other types of outlets or through direct-
mail as you have done with some of your
other products?

Sinclair: We are going to sell the computer
by direct-mail in England and the U.S.
There may come a time when store dis-
tribution is possible, but you can't really
distribute to a store until you have a much
better informed public. A very large mail-
order campaign may help do that, so it may
be possible later to distribute to stores.

Ahl: Many people buying computers to-
day, particularly at this price level, are con-
cerned with where or who can they go back
to for service, particularly if they buy a
machine by direct-mail.

Sinclair: There are two points there: the
first involves the product, the second is
who to come back to for service. We have a

permanent office in the States and we
stand behind our product at all times. We
haven't seen anything but I % or under \%
failure rate in the field in the U.K. It is a
very reliable product so we haven't got a
serious problem. We operate with service
contract houses and this is all part of the
guarantee of the product.

Ahl: Jumping back to the technical aspect
of the ZX80, it appears that although now
that it is designed for a power supply to be
plugged into standard power, it could
probably be battery operated and com-
pletely portable. Is this in your plans?

Sinclair: Yes it is. It has a very low power
consumption and could certainly run for a
reasonable time on batteries. Of course
you need a battery T.V. set as well.

Ahl: What about other peripherals, floppy
disk, mass storage, printers etc.? Are they
in the works?

Sinclair: Yes they are, we have a floppy
disk coming in about a month; the other
items should be out the middle of next
year.

Ahl: How do you feel about other alterna-
tive forms of mass storage? Some people
have said that the bubble memory is
coming down in price fast enough that it
may in two or three years replace the
floppy disk as a mass storage device. Do
you think that's likely to happen?

Sinclair: The price projections we see from
manufacturers over the next two or three
years don't suggest that to me.

Ahl: What else would you like the world
to know about you, the product, philos-
ophy etc?

Sinclair: The philosophy of the company

is very clear to lead in technology.
We've got a good start in this field and
we plan to take as good a lead as we can.
Some of the things we are developing, such
as the flat TV screen, a truly portable s\s-
tem, etc. are coming along too. Clearly we
think these are things we can do. □

Jan/Feb 1981

David Tebbutt

Clive Sinclair has surprised the world with
the launch of his attractive, hand -he Id
personal computer. Costing less than $200,
and plugging into a TV and cassette re-
corder, some now suggest the ZX80 to
represent the thin edge of a mass consumer
market wedge.

Introduction

Sinclair Research set out to build a
simple to use personal computer running
Basic and capable of breaking the
psychological price barrier of $200. Well,
they succeeded with their ZX80. Why
ZX80? No reason really except that it's
based on an NEC copy of the Z80 pro-
cessor chip . . . and it sounds nice.

The machine is available by mail order
only; there are no plans to sell it in stores —
yet. The kit version is only available in the
U.K.; in the U.S. the assembled version
costs $200 and includes an AC power
supply.

The ZX80 is amazingly light, twelve
ounces in fact, and easily held in one
hand. The low weight is achieved through
use of a moulded plastic casing just
1mm thick.

It connects quite happily to the tele-

This article has been reprinted with the permis-
sion of Personal Computer World, a British publi-
cation covering the personal computer field.
Since we cannot make frequent trips to England
we keep aware of the latest British developments
through magazines such as Personal Computer
World,

A one-year subscription to Pi W costs £8 in
the UK or £22 in the USA (via air). Write Per-
sonal Computer World. 14 Rathbone Place,
London W IP IDE. England.

vision set and the cassette recorder,
although it might take a few minutes to
find the optimal settings. Once attached
to the TV, it gives a rock steady display
(more on that later).

Hardware

I have to say that I think it very pretty
(our art director would probably beg to
differ) — the casing even has go-faster
stripes, which look suspiciously like
ventilation slots in black and white photo-
graphs (coincidence, I'm sure). I would,
however, have been happier with some-
thing rather more sturdy; ABS plastic
might have done the trick, although per-
haps at the cost of attractiveness.

The keyboard is most interesting; it's
one of those waterproof, chemical proof,
completely sealed units and it's stuck on to
the main printed circuit board (PCB).
Made of a special tough plastic, the under-
surface is printed with the key symbols so
as to eliminate any rubbing off. Between
this keyplate and the PCB containing the
metal contact strips (about five per key) is
a piece of sticky plastic containing forty
holes which line up with the "keys'*. This
material is about .006" thick and is just suf-
ficient to keep the metal underside of the

keyplate away from the contacts, except
when touched of course.

T\ ping gives a sensation of drumming
your fingers rather than of doing anything
useful. This is a totally mistaken impres-
sion because it really works rather well.
For those who a re interested, I found that a
"wiping" action was more successful than
the tapping movement usually associated
with typing. Typists may be pleased to
hear that the keys are in standard
QWERTY layout although somewhat
compressed compared to, say, the office
IBM.

Looking inside the machine, 1 find
that it's controlled by an NEC 780-1
processor chip . . .a copy of the well known
and very successful Z80. This CPU, run-
ning at 3.25MHz, does all the work for the
ZX80, including driving the TV and the
cassette recorder. You'll notice that if any
work is taking place, be it calculation,
accepting input from the keyboard or
driving the cassette, then the TV picture
disappears — only to return when the
activity is complete. This can be irritating
to observers (at a demonstration for
example) but 1 found it positively bene-
ficial when keying in programs because it
gave me positive feedback whenever a key
made successful contact.

SYNC Magazine

The Basic interpreter, operating sys-
tem, character set and editor are all held
in a 4K Byte ROM. If you are feeling
adventurous there's no reason why you
shouldn't pop your own ROM (TMS
2532) in its place.

Memory in the hasic system com-
prises IK static RAM; you can add to it
\ ia the expansion port, giving a maximum
potential of 16K. The memory expands
with the aid of plug in modules, each
designed to carry up to 3K in IK in-
crements. Thus five modules would be re-
quired to give the 16K maximum. At
switch-on the machine does a memory
check which also tells the system how
much memory is on-line. Should you re-
configure the memory, then the command
NEW will execute the memory check
cycle again.

Moving on to the "outside world"
connections, there's a cassette interface,
TV socket and a hefty edge connector.
The cassette interface comprises two
3.5mm jack plug sockets, securely mounted
on the main (and only) PCB. One connects
to the "ear" socket on the cassette recorder
and the other to the "mic" socket. There is
no facility for remote control of the cassette
motor.

Although I encountered one or two
problems at first, once working, the
cassette interface proved trouble free.
My particular recorder had a nasty habit of
recording noises when the CPU was "send-
ing out" silence. This caused the system to
get its knickers in a twist when reading
from cassette because it expected silence
just before the file header record. After a
couple of hours (what a confession) the
culprit was found — the "ear" lead, which
acts as a monitor while recording, was
setting up some sort of oscillation.
Answer simple — disconnect the "ear"
jack when recording. Another tip which
ensures trouble free loading is to move
the tape into the silent section before
issuing your LOAD instruction. Rumor
has it that the cassette operates at around
250 baud 1 believe it, although it doesn't
seem terribly important when you're only
loading the IK that 1 was.

The television connector is simplicity
itself. Plug one end of the cable (supplied)
into the ZX80 and the other into the tele-
vision aerial socket, tune to channel 2 and
you're in business. The display is magic;
rock steady and very clear although re-
versed characters (white on black) are not
so good.

I have already mentioned the bus-
iness of the display switching off every
time the processor needs to do something
else. If this drives you mad then you'll
have to forfeit some of the undoubted plea-
sures that this machine has to offer. The
screen is not memory mapped; it's treated
like a serial file — like a printer in fact -
which means that fast moving graphics are
out of the question. No doubt some clever

Technical Specification

CPU: \l( 780C-I (cop> o\ Z80)3.25 MM/

Memoiv. IK static RAM, expandable to 1 6k

Keyboard: Kcvpkue. under-surface printed

Screen: Use own television. Pixel graphics 24 lines x 32 chars.

Cassette: Use domestic audio cassette recorder.

Bus: Edge connector with 44 lines 37 from CPU, 0V, 5V, 9V, Clock.

External memory indicator and two earths.

Software: 4K ROM containing Basic. Editor and Operating System

Dick out there will take up the challenge
and fudge the system, just to prove me
wrong. More about the reasons for this in
the Software section, but anyone who is
hooked on white characters on a black
background can suitably modify the PCB,
though why they should want to 111 never
know. It's a matter of cutting one track and
making a small bridge to another.

Do you take your computer camping
with you? You'll be pleased to hear that it
can run from a car battery, provided that
the lead regulates the supply. I believe you
can buy a cigarette lighter plug with a built
in regulator . . . couple that with a portable
TV and a battery powered cassette re-
corder and you'll be the envy of the camp-
site.

The keyboard is most
interesting; it's one of
those waterproof, chemi-
cal proof, completely seal-
ed units.

Now let's look at the hefty edge con-
nector. This is where the memory ex-
pansion modules fit in, each one being
"piggy backed" on the one previous. Thus
there are always 44 contacts available for
outside use. There are 37 lines drawn from
the CPU plus 3 power lines (at 0V, 5V and
9V); the other lines comprise two grounds,
a "clock" signal and an "external memory
in use" indicator

All in all, the Sinclair ZX80 is a well
designed, well produced personal com-
puter. Memory addition comes a bit ex-
pensive at about $700 for the full ex-
pansion but Clive Sinclair tells me bigger
RAMs are on the way -- that means
cheaper expansion when they appear.

I'm sorry that there are no pictures
of the machine's innards. The fact of the
matter is that I was given one of the de-
velopment machines which had a couple
of "Veroboarded" EPROMS and a
selector IC floating around on the ends of
some pieces of wire which in turn were
soldered into the "official" ROM socket.
I thought it best to spare Mr. Sinclair's
blushes.

Software

The software of the ZX80 comprises
the Basic interpreter, the Editor and what-
ever it is that does the rest of the work
(Operating System seems too grand a
title). Rather than looking at each
separately, I shall examine them in the
order they might be encountered.

First of all the keying in of programs.
For two reasons it's an absolute joy! First
you don't have to type in many of the Basic
instruction codes, one key is sufficient;
second you cannot enter anything that is
syntactically incorrect. Some Basic in-
structions have to be entered the long way
(these are listed above te keyboard) but 29
of the instructions may be entered with a
single keystroke, while only 8 need to be
keyed in full.

As with many small computers most
of the instruction codes are stored in a
single byte. Normal Z80 machine code can
be entered using the POKE statement and
executed with the USR instruction. This
should keep the buffs happy after they
have tired of Basic. Syntax checking is
superb - it's impossible to go wrong.
Every character is checked on entry and, if
the interpreter thinks that you are going to
make a mistake, it signals with a reverse S
(for Syntax) at the point it thinks you have
gone wrong. If, later in the same line, you
correct the error, then the marker dis-
appears. What a grown up facility for such
a small machine! Incidentally, the pro-
gram lines are displayed very clearly with
line numbers, instructions, operators and
what have you being nicely spaced out.

Inside the memory, however, there's
a completely different story. The lines
of code are held as compactly as possible
with most of the commands and operators
occupying one byte each. The spaces are
removed and there are very few extra
bytes needed - for instance the new line
code is one byte, although I did notice
that the "=" operator needed one extra for
some reason. I'm sure there are others, but
I'm equally sure they are very few and
tar between. An example of the storage
requirement is as follows:

10 FOR A = 16424 TO 17424 18 Bvtes

20 PRINT PEEK(A); 12 Bytes

30 NEXT A 5 Bytes

40 STOP 4 Bytes

Jan/Feb 1981

So you see, the storage for that program
(displaying the IK memory) is 39 bytes
long — an average of 10 bytes per in-
struction. Ill leave you to work out what
sort of program you can get in 1 K. Perhaps
1 should mention that the screen buffer
uses part of the IK, as does the stack and
system control area. The stack is held at the
top of memory and "grows" down; I put
327 entries on it before it slopped accept-
ing them.

The program and variables "grow" up
into the screen buffer thus reducing the
amount of data on display. Eventually it's
possible for the program or variables to
grow so large that there's nothing left on
display. It was while experimenting with
this interesting feature that I crashed the
system. It seems the software couldn't cope
with someone entering a string 868 bytes
long! After about 424 bytes of input the
screen removed another character every
time I keyed in a new one — it was most
odd to watch.

Another way of crashing the system,
in fact the only other way I could find, is
to hit the EDIT key while in the middle of
an INPUT loop. This returns the current
program line with a syntax error which is
impossible to clear. For those who are
feeling unhappy about all this talk of
crashing systems, don't worry, it's not as
bad as it sounds. In the first place you have
to enter forty characters after the screen
has gone blank, and in the second place
you can only hit EDIT when you are also
holding the SHIFT key down.

Now it may be that, having loaded
your program, you wish to edit it. Well
once again there is some rather excellent
software to help you. The Editor enables
you to move a "current line marker" up
and down the program text. Wherever it
is you will always be able to see the marked
line and at least some of its neighbors (it's
called getting it in context). Pressing the
HOME key causes the marker to disappear
— it has in fact gone to an imaginary posi-
tion, one above the first program line.
Having reached the line to be edited press
the EDIT key and the line will be pre-
sented at the bottom of the screen ready for
you to do your worst. From now on it is as
if you are entering the line for the first time.

The benchmark* timings show the
ZX-80 to be very fast, even though I had to
introduce some extra code to make some
of the instructions work. Specifically I had
to bracket expressions like LET A=(K/ K)*
K)+K — K ... if I hadn't, the expression
would have exceeded the ZX80's
capacity. The machine can only operate on
integers and these must have values from
—32768 to 32767. I couldn't execute
Benchmark 8 because the machine has no
logarithmic or trigonometrical functions
built in.

*P( W uvcs X Benchmark programs to compare
computers

Basic

String Expressions

CHRS(n)

TLSM

STR$(n)

Integer Expressions
PEEK(n)

ABS(n)

CODE(s)

R\D(n)

USR(n)

Statements

NEW

RUN

INPUT dest

STOP

POKEn,n

CLS

LOAD
CONTINUE
PRIM
DIM (n)
RANDOMIZE n
GOSUB n

SAVE

REM

LIST n

FOR =n TO n

RANDOMIZE

RETURN

RUN n

IF n THEN stmnt

LIST

GOTO n

CLEAR

NEXT

Operations
n**n

— n

n*n

n n

n + n

n n

n - n

n > n

n < n

NOT n

s = s

n AND n

s > s
n OR n

s < s

n = number

s string

** = to the power of

Finally, it's possible to save programs
and any variables associated with them. If
you want to make use of those same
variables when reloading the program, use
GOTO rather than RUN. Although it's
possible to SAVE programs in this way, no
provision has been made to save files —
yet.

Every character is checked
on entry.

That's about it for the software; once
again, considering the size of machine and
price, I think that it's not at all bad.

Basic

The ZX80 Basic has been well
thought-out and, while it lacks some of the
elegance and sophistication of the bigger
machines, it's a very usable version of
the language.

The main limitations relate to file
handling and mathematical functions. File
handling facilities don't exist, except by
SAVEing the whole of memory (which is
probably not as daft as it sounds). It does
mean that you can save a program with all
its variables, reload it the next day,
remember to kick off with a GOTO rather
than RUN, and carry on from where you
left off. On the small memory machine it
doesn't seem that important, but on the
larger memory machines it means you can
hold some reasonable sized files together
with your program.

Benchmark timings (in

seconds)

BMI

1.46

BM2

4.69

BM3

9,18

BM4

8.95

BM5

12.7

BM6

25.9

BM7

39.2

BM8 not

performed (sec text)

The mathematical limitations are
possibly more serious. The fact is the
Basic can only handle integers in the range
— 32768 to 32767, no decimals, hence the
programmer must write a little routine for
each mathematical function that requires
decimals to be used. This should pose few
problems for those with the larger memory
machines but it will undoubtedly occupy a
fair chunk of the basic IK system.

So much for bad news; now here are
some of the good features of the language.

Taking numeric functions first, the
Basic offers up to 26 single dimension
numeric arrays of any length. It also allows
three Boolean operations — AND, OR
and NOT

The randomizing functions are worth
a mention. RANDOMIZE n sets a seed
value, while RND(n) gives a random
number in the range 1 to n. PEEK and
POKE are both available so it's possible to
read or modify memory contents; coupled
with the USR function, this means that
Z80 machine code routines can be ex-
ecuted.

Up to 26 FOR . . . NEXT loops can
be nested and the number of nestable sub-
routine calls seem to be dictated by the
amount of memory available to the stack.
On the IK machine with a short (4 line)
program, 1 ws able to get 327 subroutine
calls in before needing to RETURN.

String functions, while adequate,
could definitely be improved. The
absence of a DATA statement and the lack
of string arrays caused particular frustra-
tion. Although there are ways around
these problems, they can be time con-
suming and messy.

The functions which are available,
and which form the building blocks of
string handling subroutines, are STR$,
TL$, CODE, CHRSand INPUT. STR$(n)
returns a string of 1 to 6 characters repre-
senting the signed, decimal value of n. TL$
returns a string minus its first character,
while CODE returns the code for the first

SYNC Magazine

character in a string. CHR$(n) represents
the character whose value is n and INPUT
allows the operator to input numeric or
alphanumeric information, A nice touch
is that if the destination of input is a string
variable, then the Basic kindly provides a
pair of quotes which act not only as a
prompt, they also save a little bit of keying.

There is one trap here for the unwary,
and I fell into it. I had this nice little loop
going and after a while I got fed up with
it. Could I get out of the system — could I
heck! I hit everything in sight but all I
managed to do was crash the system (see
earlier). The trick is that if you are in an
input string loop, remove the quotes and
then put in an arithmetic expression which
will resolve outside the range — 32768 to
32767.

So, that's the Basic — I reckon that
it's pretty good under the circumstances
and in some respects I prefer it to the
Basics that do all your thinking for you.

Documentation

This comprises a programming cum
operating manual. It's very well pre-
sented, being written by Hugo Davenport
of Cambridge Consultants, with ap-
pendices by the mystery man from
Cambridge who wrote the Basic in-
terpreter. There are a few small mistakes in
the manual — none of them terribly serious
and all of them being dealt with before the
next reprint. It's probably good enough to
learn to program from it and my only
real criticisms like in the area of what it
does (or rather, doesn't do) for the
raw beginner. I lent the machine to one
such person for a few hours and here in
his reply regarding the documentation:

"I read Chapter 2 (Getting Started)
and got completely lost by the third page.
One minute it's telling me how to wire
everything up, the next there's something
incomprehensible about storing programs
on tape. I couldn't find an idiot's Guide to
getting started' anywhere."

Maybe the Operating Manual wasn't
designed with such a person in mind —
even so, novices like him must surely repre-
sent a good sized chunk of the ZX80's
ownership potential."

Future Plans

A new ROM is being developed which
will overcome most of the shortcomings
of the existing system. Being 8K instead
of 4K means that file handling routines
will enable us to read and write tapes —
even discs! This new ROM will also in-
clude the missing trigonometrical,
logarithmic and floating point arithmetic
functions.

Another area of development is on
the memory front. A 16K plug in dynamic
RAM is a distinct possibility; this will be
considerably cheaper than taking the
present $700 expansion route. A printer
is also likely to appear in due course.

Potential Use

In its present form the ZX80 offers an
ideal introduction to computing. It makes
Basic easy to learn, it's small enough for it
not to be intimidating and it's cheap
enough that, should you decide computing
is not for you, you can give it away, sell it or
whatever. Indeed it's probably cheaper to
learn Basic this way than to pay for many
of the courses around.

Teachers might buy it for their
students' use because at the price there is
no need to go through a complicated
rigmarole to get the money. The IK. ver-
sion can be used for fairly simple games
and activities, although it's likely you will
want to expand it before very long. Later,
when the file handling facilities are intro-
duced together with floating point arith-
metic, I think the machine will become
really useful, though still very much at the
personal level. Home accounts and en-
gineering calculations spring to mind im-
mediately — don't ask me why! Suddenly
the machine becomes something more
than a teaching machine or toy: it starts to
become a real computer.

Conclusion

Having just read Science of
Cambridge's claims for the machine again,
I have to say I agree with most of them. The
only point I would question is that it
offers high resolution graphics. OK, OK,
so they are playing the same game as

everyone else ... all the same 1 feel that it
should be explained. Just lately, people
have taken to calling pixel graphics, high
resolution graphics. Accordingly, what
used to be called high resolution graphics
now has to be called ultra high resolution
graphics. To put it another way, the ZX80
otters a graphics resolution of one quarter
of one character, plus you must write your
own software to be able to use it. PET is
in exactly the same boat, unless you want
to buy the high resolution add-on at
about $600.

The ZX80 appears to be a well
thought out machine both in terms of
hardware and software. It has an excellent
editor and interpreter which between
them help you avoid all sorts of nasty
pitfalls. The Basic instruction set lacks
one or two fairly important facilities —
namely file handling and floating point
calculations. Despite this, it's still a fine
machine on which to learn about com-
puting. The new ROM expected later this
year will overcome the prime limitations
leaving me very little to say except that I
hope Mr. Sinclair and his merry men of
Cambridge can cope with the expected
flood of orders and, perhaps more im-
portantly, the after sales service which is
vital in this sort of operation. □

Our thanks go to C/ive Sinclair for lending
us the machine, and to Jim West wood (its

designer) for patiently answering so
many questions.

LIN5AC

68 Barker Road

Middlesbrough

TS5 5ES

THE ZXBO COMPANION
(Second Edition)

ISBN 907211 00 3. Price
£10.00 incl. UK postage.

This beat-selling manual on the
Sinclair ZX80 covers ZXBO
BASIC, hardware and programs
and has a detailed explanation of
the ZX80 Monitor, routines and
entry points.

Crul - Operating the ZX80.

Ch.2 - Theory of Computers

Ch.3 - ZXBO BASIC.

Ch.ft - The ZX80 Monitor.

Ch.5 - Construction and

Hardware

Ch,6 - ZX80 Programs.

App.l - Comparison of Z-80

Opcodes and ZX8U Characters.

App.2 - The OK ROM.

For a cassette of ten programs
from the Companion add £4.95.

Cassette Software

All L1NSAC program packs come on single C12 cassettes with printed run instructions.
All apart from Games Pack 3 are designed for IK ZXBCPs. Price £10.00 per pack
including UK postage.

Games Peck 1 - Three Towers, Number Guessing, Mastermind, Sketcher, Hurkle,

Nim, Symbol Simon.

Garnet Pack 2 - Nine Lives, The Maze Game, Plain Sailing, Noughts and Crosses,

Chinese Puzzle, Tower of Hanoi, Battleships.

Games Peck 3 (for 2 - 4K ZX80"s} - Fruit Machine, Four-in-a-Line, Zombies.

Education Pack 1
Day Finder.
Education Peck 2

Statistics.

Maths Drill, Dot Recognition, Musical Notes, Spelling Quiz,
Graph Plotter, Prime Factors, Number Bases, Bar Charts,

Utility Pack 1 - Memory Display, Hex Code Monitor, Renumber, Memory Search.

The above ZX80 products are distributed by IMAGE COMPUTING in the United
States

Jan/Feb 1981

The Times

They are a* Changing:
The Building of
a MicroAce

Laura L McLaughlin

Back in the beginnings of the personal
computer industry, I built my first "very
own" computer with a friend. That was in
January of 1976 (less than 5 years ago). It
was one of the first IMSAI computers
(remember them?— they're one of many
companies that are no longer). The box
was about 19 1/2" X 17" X 7", weighed in
excess of 40 pounds and contained a fromt
panel, fan, power supply and a mother-
board which would hold up to 22 S-100
boards. Initially we built 7 boards; a pro-
cessor, four 4K RAM cards, a cassette
interface and a serial interface. This was a
many man-hours project— if my memory
serves me correctly, I'd say about 80 man-
hours— no small task. And at that point
our only I/O on the system consisted of 8
switches on the front panel for entering
one byte (character) at a time and 8 lights
for output of byte. Of course we had a
serial interface to drive a printer or ter-
minal (maybe even with a keyboard), but
that would have to wait until we could
afford it. We could save a program, once
loaded in through the switches, onto a
cassette and then load it into memory
from the cassette - but to do that we had to
use the switches to load the program that
could read the cassette. Please note that
at this point we had invested approxi-
mately $2000.00 in our system.

Now consider this. Today I sat down to
build another personal computer, a
MicroAce that retails for $169.00 (less
than 9% of the cost of the IMSAI), and
takes approximately 7 hours (less than
10% of the time) to build. It measures
about 8-1/2" X 7" X 1-1/2" and weighs in
at 13 ounces.

But what do I get with the MicroAce?
Well, let's look at that for a moment. It
comes with processor, cassette interface,
pressure-sensitive keyboard, video inter-
face (with built in UHF modulator so that
it connects directly to the antenna leads
on a standard TV set), power supply (an
AC adaptor just like the one you use on
your calculator that plugs into a regular
1 10 volt wall outlet), 2K of RAM memory
and a 4K Basic in ROM. Basic? When we
first built the IMSAI we couldn't even buy
a Basic that would run on it! The IMSAI
had more memory and certainly more
potential to expand (and, in fact, was
eventually developed into an extremely
powerful system), but in comparing what
is available today versus what there was
back in the "early" days of home com-
puters, there is no question that the
MicroAce is amazine.

I should mention that my background is
in software; I am not a hardware person.
Extensive exposure to the equipment has
given me a reasonable understanding of
how it works, but I am not an expert. The
only experience I have had with building
electronic kits is that with the IMSAI.

Okay, now that we've set the scene, let's
get down to the discussion of what it took
to build this machine. The first phase of
the project was to read through the
manual. Upon opening the booklet I first
saw a xeroxed sheet with a heading that
said "Important— Read this and the last
page in the manual first."

Alright, this is a newly released product
so I guess errata sheets are to be expected.
The best way to handle an errata sheet is
to transfer the corrections directly into
the manual with a colored pen. Don't be
afraid to write in the book — remember, it
is yours. This way you will not forget (or
lose) the changes. One of the changes
involved installing two jumper wires on
the back of the printed curcuit card
(PCB), but nowhere did it say when this
should be done. Since they would likely be
in the way during normal assembly, I
noted in the instructions (on page 1 1 ) that
this should be done just prior to inserting
the integrated circuits (ICs).

8

SYNC Magazine

Now to the assembly instructions them-
selves. Note that the manual is sub-titled
"The Teach-Yourself BASIC Manual."
This is not particularly misleading. Of the
66 pages, the chapter on assembly takes
10; and that contains 4 pages on tips and
component identification, 2 on board dia-
grams and 1 on a parts list. Much of the
remaining 3 pages are either diagrams or
precautions. The actual assembly instruc-
tions basically just say:

1. Install sockets

2. Install small discreet components

3. Install tape and power sockets,
voltage regulator and modulator

4. Make tape and video cables (if
necessary)

5. Insert ICs

These are indeed sparse assembly in-
structions. Now, I fully admit that the rest
of the manual goes on to explain Basic to
the novice in a very reasonable fashion,
but it seems to me that a little more detail
on the actual construction is called for
(maybe even just a checklist by compo-
nent type?). In any case, they do provide

you with some very good information on
both component identification and on
many of the precautions that should be
taken in the process of putting together
the MicroAce (or any other digital elec-
tronic circuit board kit), including such
things as how to avoid destroying static
sensitive chips. I do hope you have some
familiarity with the terminology, other-
wise you may find the instructions con-
fusing.

Having become familiar with the in-
strictions, I proceeded to compare the
parts supplied against those in the com-
ponent list. This was a relatively straight-
forward task since they provide an excel-
lent section on parts identification,
including a complete list of resistors, by
number, with their color codes. Checking
the parts off as I went along, and noting
any discrepancies, I found I had 1 extra
resistor, 1 extra socket and 2 missing
diodes. Well the extras would obviously
not be a problem, but the elusive diodes
might.

Since the next step was to locate the
positions of all the parts on the board
(using the component layout on page 7 of
the manual), I decided to look first for
where the diodes were located. Low and
behold, I saw markings for only 9 of them,
instead of the 1 1 indicated in the parts list.
Encouraging. Maybe I wasn't missing any-
thing afterall. As a double check, I went to
the schematic (pages 34-35) and once
again could see only 9 diodes. It seemed
safe to assume that the component list was
wrong.

I found the rest of the parts easily.
There was just one confusing marking on
the board layout. Since this is a new re-
lease, it did not surprise me to find extra
screenings on the board for parts no
longer necessary. These were all clearly
noted in the list of components. However,
I noticed a symbol for a transistor (TR1)
on the upper righthand corner. Once
again I went to the schematic, but could
find no indication of any transistors. With
none supplied and no other mention of it
to be found, I assumed it to be one more
unused part, so I indicated that on my
component list.

Now install the voltage regulator following the diagram below exactly

Photo 1 Check ing for all of the pa rts

Bend the regulators leads as shown (not too close to the plastic) and
bolt it down firmly to the board before soldering the 3 wires

Lastly install the modulator again bending the leads so that they fit
through the holes m the board.

Photo 2 The solder side of the MicroAce
Jan/Feb 1981

Sample page from assembly manual.

Photo 3 Beginning the assembly

Photo 4 Progress continues

Now I was ready to turn on my solder-
ing iron and begin. Following the instruc-
tions, I started with the sockets. This
practice works well not only for efficiency
of construction, but also because it means
initial soldering is done on things that are
not damaged when overheated. I found
this reassuring since I was afraid Td be a
little rusty in this department. All went
well. I was pleased to see that they had
been very careful in the placement of
markings on the board. Although things
were somewhat tight in places, nothing
was hidden as I put in the sockets.

The next task, according to the manual,
was to install the discreet components.
With no detailed instructions or checklist,
I decided to follow the component list,
checking off the parts as I put them on the
board. Once again the component identi-
fication write-up turned out to be very
useful, as it showed orientation markings
for those parts that had to be inserted in a
particular direction (the two electrolytic
capacitors and the nine diodes). First I put
in all the resistors (R1-R36), double
checked their positioning, soldered them
in place, clipped their leads and inspected
the solder joints. I then did the same with
the capacitors (CI -CI 6), then the diodes
(D1-D9) and the crystal (XI).

The instructions then call for installing
the 3 tape and power sockets (not men-
tioned in the component list), the voltage
regulator (U25) and the UHF modulator,
in that order. Following the excellent dia-
grams in the manual, this was done with
no problem. Then came the tape and
video cables. The manual states that if
you're lucky (based on availability) they
will come pre-assembled. I was not lucky.
But since I had cables available from
other equipment, I postponed this task for
later. 1 do feel that if they are going to
send unassembled cables, they should at
least provide a diagram for their
construction.

In any case, all I had left to do was the
insertion of the ICs. Or did I? No, I had
noted in my manual that this was the best
time to install the two jumpers called for
by the errata sheet. After doing that, I
inserted the 24 ICs, being careful to follow
all the precautions and tips mentioned in
the instructions (except for earthing my-
self on a cold water tap; I discovered 5
years ago that working barefoot on a tiled
floor eliminated the risk of static).

I now had a completed MicroAce com-
puter. It seemed sensible to test it before
putting it into its case, so the crucial
moment had arrived. I hooked it up to my
TV, plugged it in and there it was— a
blank screen with a K in the bottom left
corner. So far, so good.

Then I pressed a key. Nothing hap-
pened. Nothing. Well, it was time to start
checking and re-checking the board.
After spending quite some time doing just
that, looking for misplaced or incorrectly
oriented components, bad solder joints or
bent under pins, I was getting quite dis-
couraged. Yet I was determined to have a
working computer. Sure, the kit comes
with a terrific guarantee— for a flat fee of
$20 you can return it to the company and
they will repair it and send it back in per-
fect working order. But that might take a
couple of weeks. I wanted to start using it
immediately.

10

SYNC Magazine

As I said before, I am not a hardware
person, but I decided to look at the sche-
matic anyway to see if I could pin-point, or
at least isolate, the problem. I noticed
immediately that the 8 diodes along the
bottom of the board were a direct inter-
face between the keyboard and the rest of
the circuitry (going specifically to Ul 1 ). I
had checked those diodes a number of
times already and was sure they were in-
stalled correctly. Checking them again
reassured me that I was right.

I won't go through the whole frustrating
story of the next few hours trying to track
down the problem with a friend (who is a
hardware person and who also checked
the diodes). Needless to say, in the end we
discovered that the diodes were in back-
wards. What had appeared to be a yellow
diode with a green band on one end, was
in reality a clear diode with a narrow
green band on one end and a very wide
yellow one on the other. What can I say
but that I hope someone can benefit from
my mistake.

Anyway, at that point (about midnight),
it didn't matter. My MicroAce worked —
that was exciting. Forgetting all the earlier
frustration, I put it in its case and sat down
to a couple of hours of joyous program-
ming.

Photo 5 Almost done

Photo 6 Trying to locate the reversed diodes

Photo 7 The finished product

Jan/Feb 1981

11

Hurkle

220

240
250
260
270
280

O ;-; "T-*

283
284
285

j^. 'Z' O

310
320
325
330

340
350
355
360
380
420
430
440
450
460
470
480
500
520
540
610
620
630
640
650
660
670
680
690
700
710
720
730

"A HURKLE IS HIDING IN A 10 BY 10

"TRY TO GUESS THE LOCATION OF THE

"YOU GET 5 TRIES. "

"AFTER EACH TRY, I WILL TELL YOU"

"THE DIRECTION TO GO TO FIND HIM.'

"HIT NEWLINE TO START."

A*

PRINT

PRINT

PRINT

PRINT

PRINT

PRINT

INPUT

CLS

RANDOMISE

LET A=RND < 1 )

LET B=RND(10)

FOR K=l TO 5

PRINT "GUESS NUMBER " 5K

"X COORDINATE?"

X

"Y COORDINATE?"

Y
> (X-A)+ABS(Y-B)=0 THEN GO TO

GRID. "
HURKLE.

PRINT

INPUT

PRINT

INPUT

IF ABS (X-A)+ABS(Y-B)=0 THEN GO TO 500

CLS

PRINT "X=";x; "y=";y; " ";

GO SUB 610

NEXT K

PRINT "SORRY, THAT IS 5 GUESSES"

PRINT "THE HURKLE IS HIDING AT ";A;",";

PRINT

PRINT

INPUT

IF NOT CODE (A*) =62 THEN STOP

GO TO 283

PRINT

PRINT

GO TO

PRINT

"PLAY AGAIN?
A*
CODE (A$> =62

"YOU FOUND HIM
440

"GO ";

IF Y=B THEN GO
IF Y<B THEN GO
PRINT "SOUTH";
GO TO 670
PRINT "NORTH";
IF X=A THEN GO
IF XCA THEN GO
PRINT "WEST"
GO TO 720
PRINT "EAST"
PRINT
RETURN

IN ";k

GUESSES. "

lo

e

TO
TO

TO
TO

670

660

720
710

N

I

W

A Hurkle is a happy beast and lives in
another galaxy on a planet named Lirht
that has three moons. Hurkle are favorite
pets of the Gwik, the dominant race of
Lirht and . . .well, to find out more, read
'The Hurkle is a Happy Beast," in the
book A Way Home, by Theodore
Sturgeon.

In this program a shy Hurkle is hiding
on a 10 by 10 grid. Homebase is point 0,0
in the southwest corner. Your guess as to
the gridpoint where the Hurkle is hiding
should be a pair of whole numbers. After
each try the computer will tell you the
approximate direction to go look for the
Hurkle. You get five guesses to find him.

This program was written by Bob
Albrecht of People's Computer Company,
and was translated by Laura McLauglin.

THIS IS GRIO-
PovNT 3,1

\

1

Ol 2.345GT89 10

12

SYNC Magazine

Converting From Other Basics

David Lubar

While Basic is a distinct computer
language , it exists in many forms. Thus, a
program written for another machine might
have to be converted before it will work
with the Sinclair. This series will deal
with conversion techniques, in hopes of
allowing you to get as many programs as
possible running.

A command found in many Basics is
STEP. This is used in FOR-NEXT loops
when an increment other than one is
desired. For example:

10 FOR = 1 TO 9 STEP 2
20 PRINT I
30 NEXT I

This program will print the odd numbers
from one to nine. At each pass through
the loop, the variable I will increased by
two. STEP can also be negative:

10 FOR I =
20 PRINT I

30 NEXT I

10 TO 1 STEP-1

In this case, I will decrease by one on
each pass through the loop.

There is no STEP command in Sinclair
Basic. Fortunately, there is an easy way
around this. Loops are convenient, but
they can always be replaced with IF-THEN
statements. This is done by using a variable
for a counter, and checking to see whether
it is still in the desired range. If it is, the
program portion is repeated. A simple
loop such as

10 FOR I =
20 PRINT I
30 NEXT I

1TO 10

could be replaced with

10 LET I = 1

20 PRINT I

30 LET I = I + 1

40 IF K 1 1 THEN GOTO 20

Line 10 initializes the variable. After
the desired action is performed by line
20, line 30 increases the variable. Then,
at line 40, the variable is checked to
determine whether it is still within the set
limits. A value of 11 was used since we
want the action to be performed ten times.
The variable is increased and checked
after the action since this is the way it is
done when using FOR-NEXT loops. As
might be obvious now, the STEP command
is equivalent to the actions performed by
line 30, In this case, the STEP was one.
For other steps, all that is needed is a
change of the values used. For instance,
the first example could be rewritten as:

10 LET I = 1

20 PRINT I

30 LET 1 = 1 + 2

40 IFI < 10 THEN GOTO 20

For the second example, with a negative
STEP, you would use

10 LET I = I
20 PRINT I
30 LET 1 = 1-1

40 IF I > THEN GO TO 20

Notice that when replacing the negative
STEP, a > was used, while a < is used in
positive STEPS. In either case, you have
to check to see if the value has gone
beyond the desired range.

Some programs use fractional values
for STEP. In some cases you can get
around this by multiplying everything by
a constant that will make the STEP value
an integer. In other cases, where the
decimal value is essential, this won't
work.

Future articles will cover other conver-
sion techniques, showing how to get those
strange looking programs to run on the
ZX-80.

Editorial

by David Lubar

The Sinclair ZX80 is the new kid in
town; a short-lived position in this rapidly
changing field. In the past few years, several
dozen personal computers have made an
appearance. Some are thriving, others have
fallen into the obscurity of bargain sales.
We believe that the Sinclair is going to be
one of the winners; otherwise, there would
be no sense in starting this magazine. So,
what are our plans? We aim to cover many
levels, with articles that will help beginners,
as well as features for pros.

The Sinclair is an exciting machine with
a lot of potential, and we hope to reflect
this in the programs and articles we publish.
There will be plenty of games, both new
ones and conversions of classics. As new
aspects or hidden capabilities of the Sinclair
are discovered, well pass the information
on to you. As you make discoveries, we
hope you'll take the time to write articles
for us.

There is another question tied in with
this: what happens when Sinclair owners
begin to get extended Basic and expanded
memory? Inevitably, there will be a time
when our readers cover the full spectrum
from those with minimal systems to those
with fully expanded ones. This might seem
to pose a problem, but the problem is not
unique. Several of the popular home com-
puters started out as very small systems
with little memory and modest Basics. As
memory became less expensive, most own-
ers expanded their systems. For a time,
computer magazines dealt mostly with the
original configurations, and occasionally
ran an article or program aimed at expaned
systems. Later, the coverage shifted, but
the smaller systems were not ignored.

This will probably be the case with
SYNC. We'll stick to the IK RAM 4K
Basic machine now, while running a
few pieces designed for other configura-
tions. Later, there will most likely be more
attention given to expanded systems, but
plenty of coverage will still be dedicated
to the original model. In a way, this will
be determined by you. Much of our
material will come from free-lance sub-
missions. As more writers expand their
Sinclairs, we will receive more articles
and programs aimed at larger systems.
But it must be stressed that SYNC will
never ignore those pioneers who own the
original model.

Jan/Feb 1981

13

Dealing Out a Conversion

David Lubar

Sinclair owners will probably spend a
fair amount of time converting programs
from other Basics. This can be a rewarding
and educational practice or an exercise in
frustration, depending on how you go about
it. To pass on a few tips and tricks for
translating, 1*11 explain the techniques used
in getting Acey Deucy running on the ZX
80.

The first step in any translation is to get
a good idea of the functions being performed
by the program, and of the logic flow behind
these functions. Let's go through the original
listing, examine what each part does, and
see how the functions can be duplicated
on the Sinclair. Basically, the program does
the following; it deals two cards, accepts a
bet, deals a third card, checks for a win or
loss, adjusts the player's total, and checks
to see if he is broke. The first portion of
the program prints the instructions. In the
interest of saving memory, these lines were
not included in the translation. If there is
room, they can always be added later.

In lines 100 and 1 10, variables are defined.
*'N" is not used later in the program, so it
isn't included in the translation. The original
programmer probably had plans to use it
in some later version of the game and
didn't bother to remove it from the listing.
"0" holds the amount of money the player
has. The next section, lines 120 and 130,
print the player's total and then print a
blank line. While die extra PRINT statement
adds readability, it also uses memory. Like
the instructions, it can always be added
later. The program then jumps to the section
from 260 to 650 where the cards are selected
and displayed. This is where the real changes
begin to occur.

14

10 PRINT TAB(26);"ACEY DUCEY CARD GAME"

20 PRINT TAB( 15); "CREATIVE COMPUTING HQRR1SF0UN, NEU JERSEY"

21 PRINT

22 PRINT -

23 PRINT

30 PRINT"ACEY-DUCEY IS PLAYED IN THE FOLLOWING MANNER ■

40 PRINT"THE DEALER (COMPUTER) DEALS TWO CARDS FACE UP"

50 PRINPYQU HAVE AN OPTION TO BET OR NOT BET DEPENDING"

60 PRlNT"QN WHETHER OR NOR YOU FEEL THE CARD UILL HAVE"

70 PRINT-A VALUE BETUEEN THE FIRST TUQ."

80 PRINT" IF YOU DO NOT UANT TO BET, INPUT A 0"

100 N*100

110 0*100

120 PRINT-Y0U NOW HAVE ";fl;" DOLLARS"

130 PRINT

140 60T0 260

210 Q=0+H

220 GOTO 120

240 Q*Q-H

250 GOTO 120

240 PRINT"HERE ARE YOUR NEXT TU0 CARDS ■

270 A'INT<14*RNDU))*2

280 IF A<2 THEN 270
2*0 IF A>14 THEN 270
300 B=INT(14*RND(1>>+2
310 IF B<2 THEN 300
320 IF B>14 THEN 300
330 IF A>*B THEN 270
330 IF A<11 THEN 400
360 IF A*11 THEN 420
370 IF A*12 THEN 440
380 IF A=U THEN 460
390 IF A*14 THEN 480
400 PRINT A
410 60T0 500
420 PRINT-JACK"
430 60T0 500
440 PRINT-QUEER"
450 60T0 500
460 PRIMT"KIN6"
470 GOTO 500
480 PRINT-ACE"
500 IF B<11 THEN 550
510 IF B*11 THEN 570
320 IF B*12 THEN 590
530 IF B-13 THEN 610
540 IF B*14 THEN 630
550 PRINT B
560 60T0 650
370 PRINT-JACK"
380 GOTO 650
590 PRINT"QUEEN"
600 GOTO 650
610 PRINT"KING M
620 GOTO 650
630 PRINT-ACE"
640 PRINT
650 PRINT

660 INPUV'UHAT IS YOUR BET"JM
670 IF HOG THEN 680
673 PRINT-CHICKEN! I"

676 PRINT

677 GOTO 260
680 IF H<*0 THEN 730

690 PRINT"S0RRY, NY FRIEND BUT YOU BET TOO MUCH"

700 PRINT-Y0U HAVE ONLY ";Q;" DOLLARS TO BET"

710 GOTO 650

730 C=INT(14*RND(1)}+2

740 IF C<2 THEN 730

750 IF C>14 THEN 730

760 IF C<11 THEN 810

770 IF C=11 THEN 830

780 IF C=12 THEN 850

790 IF C = U THEN 870

800 IF C«14 THEN 690

810 PRINT C

620 GOTO 910

830 PR INT "JACK"

840 GOTO 910

850 PRINT H QUEEN"

860 GOTO 910

870 PRINT-KING"

880 GOTO 910

890 PRINT "ACE"

900 PRINT

910 IF OA THEN 930

920 GOTO 970

930 IF C>=B THEN 970

950 PRINT-Y0U UINM!"

960 GOTO 210

970 PRINT"S0RRY r YOU LOSE"

980 IF H<Q THEN 240

990 PRINT

1000 PRINT

1010 PRINT"SQRRY, FRIEND BUT YOU BLEU YOUR WAD"

1020 INPUT-TRY AGAIN (YES OR NQ)";AI

1030 IF AI="YES" THEN HO

1040 PRINI"0K HOPE YOU HAD FUN"

1050 END

Listing of Acey Ducey from Basic Computer Games. Copyright 1976 by
Creative Computing. Reprinted with permission.

SYNC Magazine

ACEY DUCEY CARD GAME
CREATIVE COMPUTING MORfUSTQUN, NEU JERSEY

ACEY-DUCEY IS PLAYED IN THE FOLLOWING MANNER

THE IEALER (COHPUTER) DEALS TUO CARDS FACE UP

YOU HAVE AN OPTION TO BET OR NOT BET DEPENDING

ON UHETHER OR NOR YOU FEEL THE CARD UILL HAVE

A VALUE IETUEEN THE FIRST TUO.

IF YOU DO NOT UANT TO BET, INPUT A

YOU NOU HAVE 100 DOLLARS

HERE ARE YOUR NEXT TUO CARDS
2
9

UHAI IS YOUR SET? 25

QUEEN

SORRY, YOU LOSE

YOU NOU HAVE 75 DOLLARS

HERE ARE YOUR NEXT TUO CARDS
4

to

UHAT IS YOUR BET? 25

10
SORRY, YOU LOSE
YOU NOU HAVE 50 DOLLARS

HERE ARE YOUR NEXT TUO CARDS

8
QUEEN

UHAI IS YOUR IETT
CHICKEN!!

HERE ARE YOUR NEXT fUO CARDS
6
10

UHAT IS YOUR BETT 20

10
SORRY , YOU LOSE
YOU NOU HAVE 30 DOLLARS

sample run from original Acey
game in Basic Computer Games.

Ducey

Several things are happening here. First,
a value from two to fourteen is chosen. By
using fourteen as the value of an ace (aces
are high), the cards can be compared easily.
In the original program, the first card
(variable A) had to be lower in value than
the second card (variable B). If this wasn't
the case, new values had to be used. In the
conversion, it doesn't matter which of the
two is higher. The program only checks to
see if they are the same. In this case, since
the player can't win, new values are selected
(see line 300 of the translation). Next, the
values are printed. If the value is below
eleven, a number is used. For a higher
value, the name of the card is needed. In
the original, this is done separately for
each card. To save space in the conversion,
this function was put into a subroutine
which could be used for all three cards.
The subroutine uses the variable "C". In
line 320 of the conversion, C is made equal
to A. Thus the subroutine prints the name
of the card if A is greater than ten.

At line 660 of the original, the bet is
taken. Line 670 shows a common operation
used in many programs: an inequality where
more than one operator is used. The symbols
=, < , and > are often used in pairs. In
this case, the symbols M < > " mean 'not
equal to." This can be translated using the
NOT operator. Whenever a program has
two symbols (such as >=, which means
"greater than or equal to,") the line can be
translated using NOT and the unused
symbol of the trio < , > ,and =. So a line
such as

10 IF X > = 10 THEN GO TO 50
can be translated as
10 IF NOT X < 10 THEN GO TO 50

Getting back to the program, line 680
checks to see if the player bet more than
he has in his winnings. This line could
have been translated using the trick just
mentioned. For variety, another method
was used. In this instance, the two symbols
were used, separated by a logical OR (see
Line 4 10 of the translation). Lines 730 through
890 select and print the third card. In the
translation, this is replaced with 450 through
465. Note that the lines in the original,
such as 740, that check for values less
than two or greater than fourteen aren't
needed. The RND function won't return a
value outside the desired range.

After the third card is displayed, the
values must be compared to see whether
there is a win or a loss. In the original,
since A was always less than B, the program
only had to determine whether D was
greater than A and less than B. This is
done in the series of lines from 910 to 970.
In the translation, we have to see whether
D is between A and B, regardless of whether
A or B is the higher of the original pair.
This is done in line 600. D must either be
greater than A and less than B or greater
than B and less than A. Otherwise, the
player loses.

Once a win or loss has been determined,
the program must adjust the player's total.
In the original, different routines were
used for win and loss. This is the section
from 210 to 240. To save space, just one
routine was used in the translation. This is
done in line 215. If the player lost, M will
have a negative value (see line 630) and
the bet will actually be subtracted from
the total.

Line 620 of the translation checks to
see if the player is broke. If he is, the
program goes on to line 900 where the
player is offered another chance.

That about covers the translation. Note
that on each pass through the game, the
player must hit NEWLINE to continue
(line 210). This serves two purposes. The
input stops the program temporarily,
allowing the printout to appear, and it also
gives the player a chance to read everything
before the CLS is encountered. Also,
commas are used in the print routines so
the cards will be printed on one line.

Those who are interested might try adding
some improvements to the game. For
example, in some versions of Acey Deucy,
the player loses $5 whenever a pair is
dealt. Also, in the real version, the player
has a choice of letting an ace be either
high or low if it is the first card of the two
dealt on any hand. These features could
probably be added to the existing program
with little difficulty.

Jan/Feb 1981

15

Acey Ducey

110

LET Q=100 \ A

115

RANDOMISE \ M

120

PRINT "YOU HAVE "?Q?" DOLLARS" \ M

140

GO TO 260 \ 3

210

PRINT "HIT NEWLINE TO CONTINUE" \ ^

211

INPUT A* \

214

CLS \

215

LET CNQ+M \

220

GO TO 120 \

260

PRINT "HERE ARE THE NEXT TWO CARDS"

270

LET A=RND(13)+1 I i

2S0

LET B=RND(13)+1 \ /

300

IF A=B THEN GO TO 270 \ J

310

IF A<11 THEN PRINT A, ^ 1

320

LET C=A

330

GO SUB 500

340

IF B<11 THEN PRINT B;

350

LET C=B

360

GO SUB 500

365

PRINT

370

PRINT "YOUR BET?"

380

INPUT M

390

IF NOT M=0 THEN GO TO 410

395

CLS

400

PRINT "CAUTIOUS"

405

GO TO 250

410

IF M=0 OR M<Q THEN GO TO 450

420

PRINT "SORRY, YOU ONLY HAVE ";Q?" DOLLARS

430

GO TO 370

450

LET D=RND(13)+1

460

IF D<11 THEN PRINT D

465

LET C=D

470

GO SUB 500

480

GO TO 600

500

IF C=ll THEN PRINT ".JACK",

510

IF C=12 THEN PRINT "QUEEN",

520

IF C=13 THEN PRINT "KING",

530

IF C=14 THEN PRINT "ACE",

540

RETURN

600

IF D>A AND D<IB OR D<A AND D>B THEN GO TO

610

PRINT "SORRY, YOU LOSE"

620

IF M>Q OR M=Q THEN GO TO 900

630

LET M=-M

640

GO TO 210

700

PRINT "YOU WIN"

710

GO TO 210

900

PRINT "YOU ARE TAPPED OUT. PLAY AGAIN?"

9 1

INPUT A*

920

IF NOT CODE (A*) =62 THEN STOP

TO BET- "

700

990 GO TO 110

This simulation of the Acey Ducey card
game. In the game, the dealer (the com-
puter), deals two cards face up. You have
an option to bet or not to bet depending
whether or not you feel the next card dealt
will have a value between the first two.

Your initial money is set at $100. The
game keeps going until you lose all your
money, or interrupt the program.

The original program author was Bill
Palmby of Prairie View, Illinois, and David
Lubar translated for the ZX-80.

16

SYNC Magazine

The first personal computer
forunder$20a *^

The Sinclair ZX80.
A complete computer-
only $199.95 plus $5.00 shipping.

Now, for just $199.95, you can get a
complete, powerful, full-function computer,
matching or surpassing other personal
computers costing several times more.

It's the Sinclair ZX80. The computer that
"Personal Computer World" gave 5 stars
for 'excellent value.'

The ZX80 cuts away computer jargon
and mystique, It takes you straight into
BASIC, the most common, easy-to-use
computer language.

You simply take it out of the box, con-
nect it to your TV, and turn it on. And if
you want, you can use an ordinary cassette
recorder to store programs. With the man-
ual in your hand, you'll be running programs
in an hour. Within a week, you'll be writing
complex programs with confidence.

All for under $200.

Sophisticated design makes the
ZX80 easy to learn, easy to use.

We've packed the conventional computer
onto fewer, more powerful LSI chips—
including the Z80A microprocessor, the
faster version of the famous Z80. This
makes the ZX80 the world's first truly port-
able computer (6V2" x 8V2" x IV2" and a mere
12 02.). The ZX80 also features a touch
sensitive, wipe-clean keyboard and a
32-character by 24-line display.

Yet, with all this power, the ZX80 is easy
to use, even for beginners.

Your course in computing.

The ZX80 comes complete with its own
128-page guide to computing. The manual
is perfect for both novice and expert. For
every chapter of theory, there's a chapter
of practice. So you learn by doing— not just
by reading. It makes learning easy, exciting
and enjoyable.

You'll also receive a catalog packed with
items that can make your ZX80 even more
useful. Including 27 program cassettes,
from games and home budgeting for just
$6.95, to Sinclair's unique Computer Learning
Lab. And books, hardware options and
other accessories.

ZX80*s advanced design features.

Sinclair's 4K integer BASIC has perfor-
mance features you'd expect only on much
larger and more expensive computers.
■ Unique one touch' entry. Key words

(RUN, PRINT, LIST, etc.) have their

own single-key entry to reduce typing

and save memory space.

■ Automatic

error detection.
A cursor identifies errors
immediately to prevent entering
programs with faults.

■ Powerful text editing facilities.

■ Also programmable in machine code.

■ Excellent string handling capability— up
to 26 string variables of any length.

■ Graphics, with 22 standard symbols.

■ Built-in random number generator for
games and simulations.

Sinclair's BASIC places no arbitrary re-
strictions on you— with many other flexible
features, such as variable names of any
length.

And the computer that can do so much
for you now will do even more in the fu-
ture. Options will include expansion of IK
user memory to 16K, a plug-in 8K floating-
point BASIC chip, applications software,
and other peripherals.

Order your ZX80 now!

The ZX80 is available only by mail from
Sinclair, a leading manufacturer of con-
sumer electronics worldwide.

To order by mail, use the coupon below.
But for fastest delivery, order by phone
and charge to your Master Charge or VISA.
The ZX80 is backed by a 30-day money-
back guarantee, a 90-day limited warranty
with a national service-by-mail facility, and
extended service contracts are available for
a minimal charge.

Price includes TV and cassette connectors,
AC adaptor, and 128-page manual.

All you need to use your ZX80 is a standard TV
(color or black and white). The ZX80 comes complete
with connectors that easily hook up to the antenna
terminals of your TV. Also included is a connector for
a portable cassette recorder, if you choose to store
programs. (You use an ordinary blank cassette. )

The ZX80 is a family learning aid. Children 10 and
above will quickly understand the principles of
computing— and have fun learning.

Master Charge or VISA orders call:

(203) 265-9171. We'll refund the cost of your call.
Information: General and technical— (617)
367-1988, 367-1909, 367-1898, 367-2555.
Phones (.pen Mondav-Fridav from 8 AM to
8 PM EST

Sinclair Research Ltd., 475 Main St.,
P.O. Box 3027, Wallingford, CT 06492.

To: Sinclair Research Ltd., 475 Main St., P.O. Box 3027, Wallingford, CT 06492.

Please send me ZX80 personal computers) at $199.95* each (US dollars), plus $5

shipping. {Your ZX80 may be tax deductible.)

I enclose a check/money order payable to Sinclair Research Ltd. for $

Name_

Address
City

State_

Zip

Occupation: -

Age:

L

Intended use of ZX80:

Have you ever used a computer? □ Yes □ No.

I )< 1 you own another personal computer? □ Yes □ No.

*For Conn, deliveries, add sales tax.

SY-1-

Nicomacus

fm '

One of the most ancient forms of arith-
metical puzzle is sometimes referred to as
a "boomerang." At some time, everyone
has been asked to "think of a number/'
and, after going through some process of
private calculation, to state the result, after
which the questioner promptly tells you
the number you originally thought of. There
are hundreds of varieties of the puzzle.

The oldest recorded example appears
to be that given in Arithmetica of
Nicomachus, who died about the year 120.
He tells you to think of any whole number
between 1 and 100 and divide it successively

by 3, 5, and 7, teling hin the remainder in
each case. On receiving this information,
he promptly discloses the number you
thought of.

Can you discover a simple method of
mentally performing this feat? If not you
can see how the ancient mathematician
did it by looking at lines 100-120 within
the program.

The game was originally programmed
by David Ahl and it appeared in his book,
Basic Computer Games. This version was
translated for the ZX-80 by Laura
McLaughlin.

mm?

30 PRINT "THINK OF A NUMBER BETWEEN 1 AND 100."

z

40 PRINT "YOUR NUMBER DIVIDED BY THREE HAS A REMAINDER

OF"

zz

45 INPUT A

ri

r

50 F

•RINT "YOUR NUMBER DIVIDED BY 5 HAS A REMAINDER
NPUT B

OF"

i

I

55 1

z

60 PRINT "YOUR NUMBER DIVIDED BY 7 HAS A REMAINDER

OF"

|

65 INPUT C

70 PRINT

1

~~

SO PRINT "LET ME THINK A MOMENT..."

;-

1 00

LET D=70*A+2H»-B+15+C

:

no

IF NOT DIM 05 THEN GO TO 140

120

LET D=D-105

^^^^

1 30

GO TO 1 1

s]$l§^

140

PRINT "YOUR NUMBER WAS "«DJ", RIGHT?"
INPUT A*

By i '

1 60

*^p

170

IF CODE (A*) =62 THEN GO TO 220

V!j/; ,

ftiiidijujij i

ISO

IF CODE (A*) =51 THEN GO TO 240

190

PRINT "I DO NOT UNDERSTAND ";A*;". TRY YES OR

NO. "

200

GO TO 1 60

"\lP

220

PRINT "HOW ABOUT THAT. "

230

GO TO 250

240

PRINT "I THINK YOUR ARITHMETIC IS IN ERROR."

250

PRINT

260

PRINT "WANT TO TRY ANOTHER?"

270

INPUT A*

2S0

IF NOT CODE (A*) =62 THEN STOP

290

CLS

300

GO TO 30

18

SYNC Magazine

A Weekend With the ZX-80

Joshua Singer

I have always been intimidated by com-
puters, and mathematics in general. One
look at the Sinclair ZX-80, and I was con-
fused. It wasn't what I had expected; there
were no blinking lights, or humming, and
no rows of ceiling high, pulsing units. It
looked nothing like my 1950's science fic-
tion concept of a computer. The ZX-80
was a pleasant suprise. It didn't look intim-
idating. In fact, it looked like a machine I
might even be able to operate. Another
suprise: I lifted the computer and found
that it weighed only a few ounces.

I borrowed the computer from a friend,
took it home and immediately connected
it to my battered, portable television,
which showed the clearest picture ever to
grace the screen. With the Sinclair, the
T.V., and the owner's manual in front of
me, I began my first lesson in program-
ming. The manual tells you everything
you need to know, in clear, concise, often
amusing language. The manual was so
interesting that I lost track of time, some-
thing I rarely do when dealing with
numbers and other non-literary subjects.

The book is extremely logical, begin-
ning with instructions on how to connect
the Sinclair to your television set. The
same section also explains using a cassette
recorder to store programs. The introduc-
tory portion of the manual even includes
an explanation of computer languages,
ending with a discussion of the Basic used
with the ZX-80. As a complete beginner, I
related to the way in which the booklet
explained Basic as a simplified English
dialect. It made sense, maing me realize
that to give the computer commands, I
merely had to be concise, as well as
careful in choosing my words. The book
suggested the machine was stupid, and
therefore, that one had to be careful
about the manner in which it was address-
ed. I liked that attitude because it made
me feel brighter than the computer.

The manual continued by explaining
general programming procedures, and
several computer terms. I was unable to
work my way through the entire manual,
but that was only because of my own time
limitations. By the end of the first session I

could program and run addition, multipli-
cation, and division problems. Most of
these were simple enough to do by hand,
but were a good foundation for learning
programming. The book eventally en-
ables the user/reader to execute games
and provides enough information for the
Sinclair owner to continue the learning
process individually.

With just two weekends of not terrribly
intensive study, I can now run just about
any pre-programmed cassette, as well as
doing some of my own programming. I am
no programmer, but I do find that I can
have a lot of fun playing games or learning
on the ZX-80. It is such an easy machine
to learn, that I have no doubts that I'll be
writing my own programs in the near
future.

&2M^JS7y

( *5 J
K *15 )

Poke to memory mapped screen - use your ZX80 as a
sketching pad. Character and direction control.

Tunes to your cassette recorder, with selectable
octaves, semitones and duration from a wide range
of notes. Your tune will repeat itself continuously.
For the best results, memory IK 1b necessary.

( #5 ) Hex. Loader - this routine provides a simple means

for machine code programming in Hexadecimal notation.
A 'String Rotate' demonstration program is included.
Hex. Display - this routine allowB you to inspect
the contents of memory in 64 byte blocks - just
enter the decimal address.

( #20 ) Write your own games or use the ZX80 for continuous
data monitoring. You decide how long a display will
hold before your program continues (l/60th second to
approx. 16 mins.y. A Hex. Loader and a 'top row'
keyboard scanning routine is included with a demo.

I *20 )

r vied

( *15 )

Try your skill at knocking all the bricks from the
wall before your final ball is lost. The ball starts
at '9' and decrements each time it is lost until the
game is over. The paddle moves swiftly under your
control - the game restarts automatically.

Pictures of your own creation (7x8 characters) are
displayed in rapid rotation giving animation effect.
For the best results, memory IK is necessary.

/tars , /?f/tt/strtJ ,'
( $2*} ) A simplified version of the famous arcade game.

Zap the intruders as they attempt to land. The impulse
to beat your last score lb paramount. Requires ?K memory.

No modifications to hardware whatsoever. All software is thoroughly
tested and claimed to be the most advanced developed so far.
Games are written in machine code to make maximum use of memory and
provide continuous live action without loss of T.V. synchronisation.
All programs run in IK memory unless stated otherwise.

inclusive prices for program listing, details and Air Mail postage,
(Send only £90 total if all the software listed is ordered together, .
Cheques (or S.A.E. for U.K. price list and details; tot- K.Macdonald,
26 Spiers Close, Knowle, Solihull, West Midlands, B93 9ES, ENGLAND.

Jan/Feb 1981

19

The SYNC Challenge

The editor wants you to prove your
programming skills. We at SYNC have
chosen Hammurabi from Creative Com-
puting's Basic Computer Games as the
challenge program because it is a com-
plex and refined game, We challenge you
to fit this complex game into the IK
memory of a ZX-80.

In the conversion we are seeking to
preserve as much of the original game as
possible. Therefore, the primary factor in
our evaluation of your conversion will be
the preservation of as many facets of the
game as possible. Judging will also be
based on the ease of operation and the
demonstration of good programming tech-
nique.

All programs must be submitted on cas-
sette, with a letter of explanation. Both
the cassette and the letter must be clearly
marked with the participant s name, address
and phone number. Entries received by
March 15, 1981 will be judged in time for
publication in the May /June issue.

When Hammurabi is converted for the
ZX-80, the program must be substantially
shortened. Such things as the initial direc-
tions, copyright information, and REM
statements may be eliminated completely.
The ten year results may also be deleted.
Many statements may be combined, espe-
cially those referring to the same line. In
general, the program must be streamlined
to fit the ZX-80.

Prizes

1st— A one year subscription or renewal

to SYNC, and a SYNC T shirt.

2nd— A one year subscription or renewal

to SYNC.

3rd -A SYNC T shirt.

Send all entries to:

The SYNC Challenge
39 East Hanover Avenue
Morris Plains, New Jersey 07950

Hammurabi

In this game you direct the ad-
ministrator of Sumeria, Hammurabi,
how to manage the city. The city
initially has 1 ,000 acres. 1 00 people and
3,000 bushels of grain in storage.

You may buy and sell land with your
neighboring city-states for bushels of
grain — the price will vary between 17
and 26 bushels per acre. You also must
use grain to feed your people and as
seed to plant the next year's crop.

You will quickly find that a certain
number of people can only tend a
certain amount of land and that people
starve if they are not fed enough. You
also have the unexpected to contend
with such as a plague, rats destroying
stored grain, and variable harvests.

You will also find that managing just
the few resources in this game is not a
trivial job over a period of say ten years.
Thecrisis of population density rears its
head very rapidly.

HANURABI
CREATIVE COMPUTING HQRRISTQUN, NEU JERSEY

TRY YOUR HAND AT GOVERNING ANCIENT SUMERIA
FOR A TEN- YEAR TERN OF OFFICE.

HANURABI: I IEG TO REPORT TO YOU,

IN YEAR 1 , PEOPLE STARVED, 3 CAME TO THE CITY,

POPULATION IS N0U 100

THE CITY NOU OURS 1000 ACRES,

YOU HARVESTED 3 BUSHELS PER ACRE.

RATS ATE 200 BUSHELS,

YOU NOU HAVE 2800 BUSHELS IN STORE.

LAND IS TRADING AT 24 BUSHELS PER ACRE.
HOU HANY ACRES DO YOU UISH TO BUY? 10

H0U HANY BUSHELS DO YOU UISH TO FEED YOUR PEOPLE? 2000
HOU HANY ACRES DO YOU UISH TO PLANT UITH SEED? 990

HANURABI: I BEG TO REPORT TO YOU,

IN YEAR 2 f PEOPLE STARVED, 5 CANE TO THE CITY,

POPULATION IS NOU 105

THE CITY NOU OUNS 1010 ACRES.

YOU HARVESTED 3 BUSHELS PER ACRE.

RATS ATE 16 BUSHELS.

YOU NOU HAVE 3019 BUSHELS IN STORE.

LAND IS TRADING AT 21 BUSHELS PER ACRE.
HOU HANY ACRES DO YOU UISH TO BUY? 25

HOU MANY BUSHELS DO YOU UISH TO FEED YOUR PEOPLE? 2000

HOU MANY ACRES DO YOU UISH TO PLANT UITH SEED? 1000
HANURABI; THINK AGAIN. YOU HAVE ONLY

494 BUSHELS OF GRAIN. NOU THEN,
HOU MANY ACRES DO YOU UISH TO PLANT UITH SEED? 500

HANURABI: I BE6 TO REPORT TO YOU,

IN YEAR 3 , 5 PEOPLE STARVED, 5 CAHE TO THE CITY,

A HORRIBLE PLAGUE STRUCK! HALF THE PEOPLE DIED.

POPULATION IS NOU 52

THE CITY NOU OUNS 1035 ACRES.

YOU HARVESTED 1 BUSHELS PER ACRE.

RATS ATE BUSHELS.

YOU NOU HAVE 744 BUSHELS IN STORE.

LAND IS TRADING AT 17 BUSHELS PER ACRE.
HOU NANY ACRES DO YOU UISH TO BUY?
HOU NANY ACRES DO YOU UISH TO SELL? 25

HOU NANY BUSHELS DO YOU UISH TO FEED YOUR PEOPLE? 1000

HOU NANY ACRES DO YOU UISH TO PLANT UITH SEED? 500
HANURABI: THINK AGAIN. YOU HAVE ONLY

169 BUSHELS OF GRAIN. NOU THEN,
HOU NANY ACRES DO YOU UISH TO PLANT UITH SEED? 300

HANURABI: I BEG TO REPORT TO YOU,

IN YEAR 4 , 2 PEOPLE STARVED, 12 CAHE TO THE CITY,

POPULATION IS NOU 62

THE CITY NOU OUNS 1010 ACRES.

YOU HARVESTED 1 BUSHELS PER ACRE.

RATS ATE BUSHELS.

YOU NOU HAVE 319 BUSHELS IN STORE.

LAND IS TRADING AT 23 BUSHELS PER ACRE.
HOU HANY ACRES DO YOU UISH TO BUY?
HOU NANY ACRES DO YOU UISH TO SELL? 500

HOU NANY BUSHELS DO YOU UISH TO FEED YOUR PEOPLE? 500

HOU NANY ACRES DO YOU UISH TO PLANT UITH SEED? 230

YOU STARVED 37 PEOPLE IN ONE YEARM!
DUE TO THIS EXTREME MISMANAGEHENT YOU HAVE NOT ONLY
BEEN IMPEACHED AND THROUN OUT OF OFFICE BUT YOU HAVE
ALSO BEEN DECLARED NATIONAL FINK' Mi

SO LONG FOR NOU.

20

SYNC Magazine

itv^

10 PRINT TAB(32);"HArtURABI"

20 PRINT TAB(13);"CREATIVE COMPUTING HQRRISTQUN, NEW JERSEY"

30 PRINT;PRINTsPRINT

SO PRINT "TRY YOUR HAND AT GOVERNING ANCIENT SUMERIA"

90 PRINT "FOR A TEN-YEAR TERN OF OFFICE. ":PR1NT

95 D1-0: P1=G

100 Z = 0: P*95:S=2800: H=30Q0; E*H-S

110 Y = 3; A=H/Y: 1=5; Q = 1

210 0=0

215 PRINT:PRINT:PRINT "HAMURABI; I BEG TO REPORT TO YOU,": Z=Z*1

217 print -in year-;z;v;d;"PEQPle starved,";i;"Cahe to the city,

218 P»PH

227 IF Q>0 THEN 230

228 P=INT(P/2)

229 PRINT "A HORRIBLE PLAGUE STRUCK! HALF THE PEOPLE DIED."

230 PRINT "POPULATION IS NOU";P

232 PRINT "THE CITY NOU DUNS" ; A ; "ACRES. "

235 PRINT "YOU HARVESTED" ;Y;"BUSHELS PER ACRE."

250 PRINT "RATS ATE";E;"BUSHELS. M

260 PRINT "YOU NOU HAVE" ;S; "BUSHELS IN STORE.'*; PRINT

270 IF I«11 THEN 860

310 C = INTMO»RND<! )): Y=C+17

312 PRINT "LAND IS TRADING AT" ; Y ;"BUSHELS PER ACRE."

320 PRINT "HOU HANY ACRES DO YOU UISH TO BUY";

321 INPUT Q: IF Q<0 THEN 850

322 IF Y»Q<=S THEN 330

323 GOSUB 710

324 GOTO 320

330 IF 0*0 THEN 340

331 A=AtQ; S*S-Y*Q: C=0
334 GOTO 400

340 PRINT "HOU MANY ACRES DO YOU UISH TO SELL";

341 INPUT 0: IF Q<0 THEN 850

342 IF Q<A THEN 350

343 GOSUB 720

344 GOTO 340

350 A=A-0: S»S+Y*0; C*0
400 PRINT

410 PRINT "HOU MANY BUSHELS DO YOU UISH TO FEED YOUR PEOPLE";

411 INPUT Q

412 IF Q<0 THEN 850

418 REM ••• TRYING TO USE HORE GRAIN THAN IS IN SILOS?

420 IF Q<=S THEN 430

421 GOSUB 710

422 GOTO 410

430 S=S-Q: C = 1: PRINT

440 PRINT "HOU NANY ACRES DO YOU UISH TO PLANT UITH SEED";

441 INPUT D: IF D = THEN 511

442 IF D<0 THEN 850

444 REN *** TRYING TO PLANT MORE ACRES THAN YOU OUN?

445 IF D^A THEN 450

446 GOSUB 720

447 GOTO 440

449 REN ••* ENOUGH GRAIN FOR SEED?

450 IF INT(D/2X=S THEN 455

452 GOSUB 710

453 GOTO 440

454 REN ••* ENOUGH PEOPLE TO TEND THE CROPS?

455 IF D<10»P THEN 510

567 PRINT
710 PRINT

460 PRINT "BUT YOU HAVE ONLY";P;"PE0PLE TO TEND THE FIELDS! NOU THEN,"
470 GOTO 440

510 S=S-INT(D/2)

511 60SUB 800

512 REN • ** A BOUNTIFUL HARVEST)
515 Y«C; H»D»Y: E=0

321 GOSUB 800

522 IF INT(C/2)OC/2 THEN 530

523 REN *** RATS ARE RUNNING UILD! 1
525 E*INT(S/C>

530 S*S-E*H

531 GOSUB 600

532 REH *** LET'S HAVE SONE BABIES

533 I = INT<CM20*AtS)/P/1GO*1)

539 REN ♦»* HOU NANY PEOPLE HAD FULL TUNNIES?

540 C=INT(Q/20)

541 REN ♦*♦ HORROR, A 1 5Z CHANCE OF PLAGUE

542 0=INT(10*(2*RND(1)-.3M

550 IF P<C THEN 210

551 REH »*• STARVE ENOUGH FOR INPEACHHENT?

552 D«P-C: IF D>.45*P THEN 560
353 Pl»( (Z-1 )*P1+D*100/P)/2
555 P=C: D1=D1+D: GOTO 215

560 PRINT: PRINT "YOU STARVED" ;D; "PEOPLE IN ONE YEAR!!!"

565 PRINT "DUE TO THIS EXTRENE MISMANAGEMENT YOU HAVE NOT ONLY"

566 PRINT "BEEN IMPEACHED AND THRQUN OUT OF OFFICE BUT YOU HAVE"
"ALSO BEEN DECLARED NATIONAL FINK!!!!": GOTO 990
"HAMURABI: THINK AGAIN. YOU HAVE ONLY"

711 PRINT S;"BUSHELS OF GRAIN. NOU THEN,"

712 RETURN

720 PRINT "HAMURABI: THINK AGAIN. YOU OUN ONLY" ;A;"ACRES. NOU THEN,"
730 RETURN

800 CMNT(RND(1)*5>t1

801 RETURN

850 PRINT: PRINT "HAMURABI: I CANNOT DO UHAT YOU UISH."

855 PRINT "GET YOURSELF ANOTHER STEUARDMIM"

857 GOTO 990

860 PRINT -IN YOUR 10-YEAR TERN OF OFFICE, ";P1 ; M PERCENT OF THE"

862 PRINT "POPULATION STARVED PER YEAR ON THE AVERAGE, I.E. A TOTAL OF"

865 PRINT DISPEOPLE DIED"": L = A/P

070 PRINT "YOU STARTED UITH 10 ACRES PER PERSON AND ENDED UITH"

875 PRINT L;"ACRES PER PERSON."; PRINT

880 IF P1>33 THEN 565

885 IF L<7 THEN 565

890 IF P1>I0 THEN 940

892 IF L<9 THEN 940

895 IF IF Pl>3 THEN 960

896 IF LOO THEN 960

900 PRINT "A FANTASTIC PERFORNANCE ! ! ! CHARLEMAGNE, DISRAELI, AND"
"JEFFERSON COMBINED COULD NOT HAVE DONE BETTER! " :60f0 990
"YOUR HEAVY-HANDED PERFORMANCE SMACKS OF NERO AND IVAN IV."
"THE PEOPLE (REMAINING) FIND YOU AN UNPLEASANT RULER, AND,"
"FRANKLY, HATE YOUR GUTS I • *:60T0 990

"YOUR PERFORMANCE COULD HAVE BEEN SQHEUHAT BETTER, BUT"
"REALLY WASN'T TOO BAD AT ALL. "J INT (P*.8*RND( 1) ) J "PEOPLE"
"DEARLY LIKE TO SEE YOU ASSASSINATED BUT UE ALL HAVE OUR"
"TRIVIAL PROBLEMS."
FOR N=1 TO 10: PRINT CHRK7);: NEXT N
"SO LONG FOR NOU."; PRINT

905 PRINT

940 PRINT
945 PRINT
950 PRINT
960 PRINT
965 PRINT
970 PRINT
975 PRINT
990 PRINT:
995 PRINT
999 END

21

J to be continued. ..

AAORE SPECTACULAR THAN STAR WARS I
FLASHIER THAN FLASH GORPON •
SEXIER TMAN SATURN ^ K ^ ON *
PeEfeRTHAN BLACK h5L'E.»
AK.n H l, APel? "™ AN AAARS NEEPS WO/WEN*
...ANP BROUGHT T2> YOU AT AN INCRPPibTv L/Eii
fOf-T, AN(7 IN AWESOWELV R?2r TASTE BV tup W

k,... creative compatiRg /

• SPACEHAWK/

Tow us NEKr ISSUE TOR: . * _

"ATTACK of the GVTcHQlfZf"

28

^

A one-hour LP record of eight synthesizers may
change your views about computer music forever

Binary Beatles

by David Ahl

Computer music. Who needs it? It's mostly
boring beep, beep, beeps or wildly modern
stuff. It's certainly nothing you'd want to
listen to more than once. That's what I thought
about computer music and most of my friends
agreed.

In 1978 I entered Yankee Doodle Dandy
into my Software Technology system just
to be different. Dick Moberg heard of it and
asked me to perform in the Philadelphia
Computer Music Festival. I agreed expecting
to be the only one with something out of
the ordinary. I was wrong.

Computer Accompanist

Nine individuals and groups performed
in the festival. There were the usual Bach
pieces but even they were different. Gooitzen
van der Wal performed the last movement
of the 2nd Bach Suite in a unique way. He
played the flute solo while using the computer
as accompaniment.

Then Dorothy Siegel did the same thing,
playing the clarinet solo part of Wanhals
Sonata in b flat. The audience went wild.

Hal Chamberlin played Bach's Tocatta
and Fugue in d minor. But also with a differ-
ence. He used a large computer before
hand to 'compute'' the waveform of every

instrument playing every note. It took one
hour of computation time for each two min-
utes of playback time. The result could hardly
be distinguished from the organ in the
Hapsburg Cathedral.

Don Schertz had a home brewed synthe-
sizer truly mounted on a breadboard that
allowed him to control 25 parameters of
each note. It produced spectacular sounds
in his arrangement of Red Wing.

Singing Computer

In 1962, D.H, Van Lenten at Bell Labora-
tories produced the first talking computer.
Bell engineers taught it to recite the soliloquy
from Hamlet. Then they went one step further
and taught it to sing Daisy both alone and
accompanied by another computer. This
was also performed at the festival.

Yes, the Beatles were represented. Andrew
Molda played Hey Jude on his COSMAC
VIP system with a program called PIN -8
(Play it Now).

Superb Quality Recording

All these pieces and twelve others were
recorded with broadcast quality equipment.
Because of audience noise, eight were re-
recorded later in a studio. We then took
these tapes to Tru-Tone. a top recording

studio and cut a lacquer master. It was a
long session since the recording engineers
insisted upon analyzing the sound from every
source and setting up the equilization curves
accordingly. It took over 1 2 hours to produce
a one-hour lacquer master.

Finished recordings were then pressed
on top-quality vinyl and inserted into liners
and record jackets. These were then shrink
wrapped in plastic for maximum protection.
We guaranteee that every LP record is free
from defects or we will replace it free of
charge.

The extensive descriptions of each of the
eight synthesizers and the festival would
not all fit on the jacket so we've included an
extra sheet with each record. This entire
package is mailed in a protective corrugated
package to insure that it reaches you in
mint condition. The cost is a modest $6.00
postpaid in the U.S. and $7.00 foreign. Send
order with payment or Visa, MasterCard or
American Express number to Creative Com-
puting, Morris Plains, NJ 07950.

This LP record contains one hour of eight
computer music synthesizers that you'll listen
to over and over again. Send in your order
today at no risk whatsoever.

creative
computing

Morris Plains. NJ 07950
Toll-free 800-631 -81 1 2

(In NJ 201-540-0445)

J

available
by mail
order only

$14.95

(plus $1 shipping
and handling)

Other books in preparation

include:

ZX80 Machine Language

Programming

30

This Book is Excellent!"

— Clive Sinclair

The unique book contains 30 programs all designed to fit in the basic 1 K version of

the SINCLAIR ZX80H

With this book you will realise that the ZX80 is more powerful than you ever imagined!

1 1 2 pages packed full of solid information!

BLACKJACK - actually contains a full pack of cards, shuffles them, keeps track of

the dealer and player totals, and the money bets, all within 1 K.

Dr. ZX-80 - a truly conversational program: DR. ZX-80 is your personal computer

analyst.

LINE RENUMBER - an invaluable program which automatically renumbers lines

and puts order to your programs.

MEMORY LEFT - an incredible routine especially useful with only 1K, which lets

you know to the byte how much memory is left. This also illustrates USR routines.

GOMOKU — the computer challenges you to this complex Japanese game, incredibly

this program including display of the 7 x7 board fits into 1 K — it only does so because

it uses the display as memory!

Other programs included are HORSE RACE, LUNAR LANDER (with moving spaceship

display), NOUGHTS AND CROSSES, NIM, SIMPLE SIMON, HANGMAN, LIFE:

MASTERMIND, PINCH and 16 others!

WOGRtfKs

Ton

TH{

SlH C£AtR
&S0

IK

Castle Doors

Weldon J. Horton Ph.D

4
6

10
12
14
16
18
20

24
26
28
30

34

36

40
42

44
46
48
50

52
54
56
58
60

64

TO CA3TLE DOORS"

< 300 )
( 50 )

— Wizard "s
— Start i ri3

strength —
strength of pi aver

"YOUR STRENOTH IS

PRINT

PRINT

PRINT "WELCOME

PRINT

LET B=RND

LET C=RND

PRINT

PRINT

PRINT

PRINT

PRINT

PRINT "PRESS 4 TO OPEN A DOOR, PRESS 5 TO FIOHT THE WIZARD"

RANDOMISE
LET D=RND

A=0

E=RND

F=RND

G=RND

H=RND

LET

LET

LET

LET

LET

INPUT

CLS

( S )

( 50 )
(100)
( 25 )
(15)

— D o o r select o r - -
— Initializes monste
— Size of acceptable
— Chance of set tins
--Gain in strength o
— Loss of strength o

r strength —

bribe---
caught on run option
n win over monster —
n run option---

IF
IF
IF
IF
IF
IF
IF
IF
IF
IF
UF
IF

0=5
D=l
D=l
D=2
D=2
D=3
D=3
D=4
D=4
D=5
D=5
D=6

THEN GOTO 176

THEN LET A=RND (20)

THEN LET A$=" CYCLOPS"

THEN A=RND (30)

THEN LET A*="WITCH"

THEN LET A=RND (40)

THEN LET A$=" DRAGON"

THEN LET A=(50)

THEN LET A$=" GARGOYLE"

THEN LET A=(60)

THEN LET A*=" ZOMBIE"

OR D=7 OR D=S THEN GOTO

— Strength of
— Monster n

1 60

PRINT

monster in line belou —
a me —

Castle doors is an adventure game that
presents a new challenge with each play-
ing, and the opportunity for easy adjust-
ment of difficulty if the Wizard is winning
too much, or too little of the time.

You, the player, have the ultimate task
of defeating the evil Wizard, but first you
must gain strength and experience by
confronting the strange denizens of the
Wizard's enchanted castle. Behind each

80

34
86

y o

90

92

94

96

98

1 00

1 02

104

1 06
1 08

109
110
112
114
116

118
120
122
124
126
128
130
132

134
136
138

140
142
144
146
143
150
152
154
156
1 58
160
162
164
166
168

170
172
174
176
178
180
1 82

184

PRINT

PRINT "YOU MAY: FIGHT=1 BRIBE=2 RUN=3
INPUT N
CLS

IF N=2 THEN GOTO 124
IF N=3 THEN GOTO 143
IF C<A THEN GOTO 176
PRINT
PRINT
PRINT
PRINT
PRINT
PRINT
TO FIGHT
INPUT Q
CLS
PRINT-
PRINT

if q>c then goto 94

if q>a or q=a then let c=c+g

if 0>a or q=a then print "you win

brave adventurer"

if q<:a then let c=c-q

print "you lose to

"YOUR STRENGTH IS

"HOW MUCH STRENGTH
WITH?"

DO YOU WANT

THE

LET C=C-P+G
PR I NT "BR I BE

IF Q<A THEN

GOTO 12

PRINT

PRINT

PRINT "YOUR STRENGTH IS ";C

PRINT

PRINT "HOW BIG A BRIBE DO YOU

WANT TO OFFER?"

INPUT P

CLS

IF P>E OR P=E THEN

IF P>E OR P=E THEN

IF P<E THEN PRINT "BRIBE

IF P<E THEN GOTO 66

GOTO 12

PRINT

PRINT

IF F=50 THEN GOTO 176

PRINT "YOU GOT AWAY FROM THE MONSTER"

LET OC-H

GOTO 12

PRINT

PRINT

IF D=6

IF D=6

IF D=7

A*

ACCEPTED"
REFUSED"

most offer you only of of three alterna-
tives: fight the monster and pass through
the door, bribe the monster to let you
pass, or you can run away from the
monster.

After chosing to fight the monster, you
must decide how much strength to fight
with. If you lose, you lose the strength
you fought with; if you win, you win addi-
tional strength. If your total strength is
less than the strength of the monster
whom you are fighting, you lose the
game.

If you chose to bribe the monster to let
you pass, it may refuse your bribe, and
you must decide what to do next: fight,
offer a bigger bribe, or run away. If your
bribe is accepted you lose the bribe and
gain the same amount of strength points
you would have had if you had fought the
monster and won. Be warned, however,
that a successful bribe can easily result in
an overall loss of points.

If you chose to run away you will, natu-
rally, lose some strength. Also, the
monster has a one in one-hundred chance
of catching you and ending the game.

When you feel that you are ready, you
may chose to fight the evil Wizard. The
battle is short, fierce, and has the imme-
diate outcome of either total victory or
defeat.

This program is written in such a
manner as to make the adjustment of all
strength and penalty values quite easy.
Messages printed in the course of the
program run have been adjusted to print
correctly on the screen by the addition or
delection of internal spaces. Comments
have been added to the program listing in
order to identify those values that you
might want to change as you become
more familiar with the program, in order
to customize it to your preferences. You
will note, that even if you are called upon
to fight the same type of monster twice in
a row, that each individual monster with-
in a type posesses individual character-
istics, withing the set limits. Only the
power of the evil Wizard remains con-
stant during each game.

THEN
THEN
THEN

A PRINCESS AND GAIN- 50 POINTS'

PRINT "SAVE
LET OC+50

PRINT "FAIRY GIVES YOU A MAGIC POTION
THAT DOUBLES YOU STRENGTH"
IF D=7 THEN LET C=C*2

IF D=8 THEN PRINT "A GIANT BAT CARRIES YOU TO ANOTHER DOOR
GOTO 12
PRINT
PRINT
IF OB OR C=B THEN PRINT "THE WIZARD

IS
IF CCB OR C<A OR F=50 THEN PRINT "YOU F

DEFEATED-YOU
DUGHT BRAVELY,

WIN"

BUT WERE
STOP

DEFEATED-GAME OVER"

Jan/Feb 1981

31

Draw a Picture

Howard Branch

7 THEN TO TO 128

K

IBS PRINT

110 PRINT

126 PRINT "SIZE FAD

130 INPUT N

140 IF N < 3 OR N >

150 DIM A «::N * N - 1 >

200 CLS

216 FOR K « 1 TO N

228 LET *.J ■ N + 1

230 PRINT J,

240 FOR I - 1 TO N

256 PRINT CHR* CA<J - N - 1 + N * I )

260 NEXT I

276 PRINT

286 NEXT K

296 PRINT

366 PRINT ,

316 FOR I =« 1 TO N

326 PRINT I;

330 NEXT I

346 PRINT

460 PRINT "ENTER COORD"

416 INPUT X

426 IF X «' 8 THEN GO TO 560

436 PRINT X

446 LET J - X / 18

450 LET I - X - 10 * J

466 PRINT "ENTER CHAR CODE"

470 INPUT X

430 LET A<J - N - 1 + N * I>

490 GO TO 200

560 PRINT "CODES USED:"

510 FOR K ■ 1 TO N

526 LET J « N + 1 - K

530 PRINT "LINE: ".; J,

540 FOR I ■ 1 TO N

550 PRINT A<J - N - 1

560 NEXT I

570 PRINT

5S0 NEXT K

+ N * I>j "

A new house. A new neighborhood.
We've all been through it. Last time, I
remembered, it took me two or three
years before I met most of the people on
my block. This move, I was determined
that would not happen.

My solution? An open house a few weeks
after I moved in. It forced me to get
settled fast; I didn't want my neighbors
climbing over packing cartons.

I didn't know how many people to expect
and whether I'd be able to entertain them
all at once, so I set up two computers
(borrowed from work) on the lower floor.
One was an Apple, the other a ZX-80.

Naturally the Apple equipped with two
ALF music synthesizers playing stereo
music (accompanied by spectacular color
graphics of the notes being played attracted
the most initial attention).

But then some people discovered the
Sinclair in the other room. "What's this?"
and "It can't be a real computer" were
the typical comments.

I had seven or eight games on tapes,
some of which I loaded in and demon-
strated. Some people were interested.
Others started drifting back to the wine
and cheese. Then I loaded in Draw a
Picture.

This was the first program I had ever
keyed into the ZX-80. 1 was looking for a
short program to try out the machine,
and I was interested in the graphics. This
seemed ideal. And so it was.

Within 15 minutes I had made a face.
(Why is the first thing one usually drawas
with paint, computer or charred stick
usually a smiling face?) I changed the
expression, ears, nose, eyebrows and all
the other features at least five times. What
fun I think I skipped lunch that day.

My guests also made faces on the ZX-
80. First a happy face. "Oh, let me try"
said one previously timid woman. She
made a face with a large beard. Another
woman felt that a squarish, robot-type
face was more appropriate.

32

SYNC Magazine

At this point I broke through the crowd
and quickly "drew" a small dog. After all,
I reasoned, computers can do more than
draw faces. But alas, they would have
none of it, and I was unceremoniously
elbowed aside for yet another face.

As the guests drifted out, I noticed that
the computer crowd downstairs was show-
ing no such inclination. Interestingly
enough, this time the Apple had been
deserted and the crowd was around the
ZX-80 with Draw a Picture.

You too can draw faces with your ZX-
80. You can draw small dogs, or even
other things like boats, flowers and space
ships. But don't try to do it with a crowd
standing around; all they want are faces.

Draw a Picture is from 30 Programs for
the ZX-80, published by Melbourne House,
Glebe Cottage, Gleebe House, Station
Road, Cheddington, Leighton Buzzard,
Bedfordshire, England, and costs $14.95
in the U.S. or £ 7.45 in the U.K.

"71 7Z 73 7* -15 7b 77

4>l (o1 U U ^ Up &7

?■ 5* 9* <7* 5*7 91 ^

41 42 4* 44 4^ 4U +7

51 32 35 54 Si? Zi* V7

Zl 22 23 Z4 25 It* 27

VI 12 13 14- t<7 1(p 17

When the program says "ENTER
COORD," enter a single number from
the grid numbering diagram. If you enter
0, the program will give you a summary
of what codes you used at each location.
When the program says "ENTER CHAR
CODE/" enter the code of the graphics
character you want to appear on the screen.
If you want to erase a previous character,
enter 0.

Jan/Feb 1981

Available from the keyboard:

D

3 y

E

5 h

.

7 a

M

9 ■

H

11 ■

10

Not available from the keyboard:

129

128

130

132

m

136

Other useful 'graphic' symbols:
6 £ 18 - 19 +
20 # 23 > 21 <

a

131 H

a

133 L

9

m m

H

B

33

Pounds and Pence,
Dollars and Cents

Leonard Gaunt

The new ROM for the ZX80 may be available before these
words are in print. It remedies a lot of the defects of the
original ROM. It gives floating point facilities, trigonometric
functions, keyboard access to reversed characters and many
other useful functions.

For those who still have the old ROM, there is no way of
dealing with pounds and pence, or dollars and cents, is there?

As a matter of fact, the answers are 'yes'.

Leonard Gaunt, 44 Hatherop Rd.. Hampton.
Middlesex. TW12 2RF.

1 LET J

2 LET K
5 PRINT

10
20

f' . I

30

40

50

60

70

SO

90

1 00

310

311

315

320

321

324

LET
LET
FOR
LET
LET
LET
LET
LET
LET
GOSUB
NEXT

B

'ADD"
T =
T2 =

N =

1 TO
RND ( '

= RND (99)

A

ri -

A2

:< =

Y = A2
T = T +

T2 = T2
2000
N

4

1-1

+

A2

-:( )

LET X
LET Y
PRINT
PRINT

PRINT
PRINT
PRINT
PRINT
PRINT
GOSUB

= T

"PRINT YOUR ANSWER'

3000
3005
30 1
3020
3025
3026
303 1
3032
3035
3040
3070
3090
3 1 00
3110
3130

4000
40 1

"PRE::

"THE
3000

DECIMAL POINT"

2000 IF Y < 100 THEN
2010 LET Y = Y - 100
2020 LET X = X + 1
2030 GOTO 2000

2033 PRINT

2034 PRINT

2035 IF X < 10
2040 IF X <: 10
2050 IF NOT X ■■
2060 IF NOT X «
2070 RETURN

SOTO 203!

4040
4050
4055
4056
4060
4065
4070
4080

There are ways of getting round the problems. A useful
educational program, for example, is to teach kids to add up
dollars and cents, or what have you. That can be done in a
relatively simple manner, as Program 1 demonstrates. This is
a program that goes on indefinitely setting new sums.

This program is self-explanatory: It asks you to add four
randomly produced amounts from 1.01 to 99.99.

It asks you to print the answer using Newline instead of the
decimal point.

Subroutines line up the decimal point, produce the after
the decimal point where required and add the whole numbers
and the decimals separately. Your answer and the correct
answer are printed and you are told whether you are right or
wrong.

You are then invited to press Newline for another sum or S
for you score.

The program produces new sums indefinitely.

A

B

10

B •

A; ". ";

THEN PRINT "0";B
I 10 THEN PRINT B

INPUT
PRINT
PRINT
INPUT
IF B ■••:
IF NOT
PRINT
PRINT-
PRINT
GOSUB
PRINT

IF A = X AND B = Y THEN GOTO 4000
PRINT "YOU WERE WRONG"
LET K = K + 1
GOTO 4040

"THE
2000

ANSWER I!

PRINT
LET J

" THAT
= J +

IS
1

RIGHT"

NEWLINE INSTEAD OF"

PRINT
PRINT
PRINT
PRINT
INPUT
CLS
IF 1%
IF 1%
" RIGHT

"PRESS NEWLINE FOR ANOTHER SUM"

" OR
Z$

FOR YOUR SCORE"

— It Q '»

THEN i
THEN

SOTO 5
PRINT

"YOU GOT

J!

AND Y < 10 THEN PRINT , , " "

AND NOT Y < 10 THEN PRINT , ,

10 AND NOT Y < 10 THEN PRINT

10 AND Y < 10 THEN PRINT , .

AND
IX?"

K; " WRONG"

O"

x;
X;

0"

Y

Y
Y

Y

34

SYNC Magazine

10
20
30

40
50
60
70
80
90
1 00

no

1 20

130
1 40
150
160

170
130
190

200
210
220
230
240
250
260
270
230
290
300
310
320
330

■-. •-• cr
O O ■_'

340
350
360
370
380
390
400
410
420
430
440
450
460
470
4 SO
490
500
510
520
530
540
550
560

"WHAT
A$

IS YOUR NAME'

- o
" DO

"TYPE E FOR EASY; H OR D

B*

"OK,

:A*

'HERE ARE
= 1 TO 10
= RND(IO)
= RND(IO)
3 OR B <
-■ "D" THEN

"D" OF B* -

IS

"WHAT
T
A*B THEN GOTi:

PRINT

INPUT

CLS

LET X

PRINT

PRINT

PRINT

PRINT

INPUT

CLS

PRINT

PRINT

PRINT

FOR Z

LET A

LET B

IF A

IF B$

IF B*

PRINT

PRINT

PRINT

INPUT

IF T i

GOTO 320

CLS

PRINT "RIGHT"

PRINT-
LET X = X + 1

NEXT Z

GOTO 360

CLS

PRINT "WRONG,

PRINT ". ";A;

PRINT

NEXT Z

PRINT "THAT IS ALL,

PRINT

PRINT

PRINT

PRINT-
PRINT

PRINT

PRINT

PRINT

PRINT

INPUT

IF D*

CLS

PRINT

PRINT

PRINT

PRINT

PRINT
PRINT

PRINT
PRINT

YOU WANT EASY, A LITTLE HARDER, OR DIFFICULT QUESTION:;

10 QUESTIONS

: THEN
LET A

GOTO 150
= A*2
H" THEN

A; " TIMES

260

LET B = B*2

b Multiplication tables

I haven't yet got round to making the ZX80 multiply and
divide decimals but Program 2 is a simple •multiplication
table' teacher. It is a talkative' program offering three grades
of difficulty, setting ten questions, giving the score and inviting
further participation.

5 A*

TIMES

:B;

:A*

' ; A*B

" YOU SCORED

OUT OF 10'

'<c <*

"DO YOU WANT ANOTHER 10'

"TYPE
D*

__ if y* 1 1

Y FOR YES

N FOR NO"

THEN GO TO 30

"THANK YOU,

A*

'GOODBYE FOR NOW"

"BUT PLEASE COME BACK"

11 When you're through Dad, I want to write a
program to experiment with the effect of a
different coefficient on a plot of a polynomial of
the form Y (X( = A*X + B*X + C."

Jan/Feb 1981

35

1 LET .J -

2 LET ,J2 -

E3ocMi

3 LET H =

q DaSII

4 LET H2 ■

5 LET G -

6 LET G2 -

7 LET K =

8 LET K2 =

o

9 LET L =

10 LET L2

s

11 LET M -

12 LET M2

m

15 LET Z ■

16 LET Z2

-

45 PRINT "

ACCOUNT £P CATEGORY'

47 GOSUB 6

00

50 INPUT A

»

60 IF A*S

= "T" OR A* ■--- "TC" THEN C

70 INPUT B

80 INPUT E

..1

85 IF B <

THEN LET B2 = -B2

90 INPUT C

110 PRINT

ft*;

120 LET I

- 15

130 LET X

- B

140 LET Y

- B2

150 GOSUB

2000

155 GOSUB

1 000

157 GOSUB

2050

160 LET 2

- Z +■ B

170 LET Z2

! » Z2 + B2

195 LET I

= 2 5

200 PRINT

c

210 GOSUB

5000

250 GOTO 5

JO

270 GOSUB

600

290 PRINT

"TOTAL"?

300 LET' I

■ 15

310 LET X

— "7

320 LET Y

ss 7 2

325 GOSUB

9000

330 GOSUB

2000

335 GOSUB

.1 000

339 GOSUB

2050

340 IF A*

■ "TC H THEN GOTO 345

342 GOTO t

5 00

345 PRINT

346 PRINT

"CATEGORY TOTALS"

363 PRINT

ii i it

. - « L 7

369 LET X

= H

370 LET Y

- H2

375 GOSUB

8000

379 PRINT

■I -in

» • • •£, ?

380 LET X

« J

331 LET Y

= J 2

385 GOSUB

sooo

337 PRINT

• • m w 7

388 LET X

= K

389 LET Y

=s K2

Basic Accounting With Decimal Currencies

Program 3 is very complicated. It keeps accounts, in a way.
It prints out the account name or number, adds and subtracts
cash amounts, splits them into categories or groups, gives one
grand total and six sub-totals. Of course, it is rather limited by
the availability of display space. The 'Continue' facility can
be used but it really needs a printer.

This program allows the entry of account number, name.
etc., plus a column of pounds and pence, or dollars and cents,
and a category column.

The amounts can then be totalled in one grand total and six
subtotals by category number.

iOTO 270

Data entry is in the form:

1 Account number, name, etc. (any string) — newline

2 Pounds/dollars — newline — pence/cents— newline

3 Category of account (any number, normally 1 to 6) — new-
line

Note that the decimal point is not used but that .50 must be
entered as 50 and not 5 as in calculator usage. The entry of a
single figure after the decimal point is treated as one-
hundredth part, i.e. 5 is treated as 05.

Debits (minus figures) are entered in the normal way e.g.
-2566 newline 09. There is no need to put the minus sign
before the decimal entry.

After the entry of the category number, the details in 1,2 and
3 are printed. Repeat for as many entries as required.

When all entries have been made, enter;

T newline to obtain main total only OR

TC newline to obtain main total and subtotals

If further entries or corrections are necessary, enter

C newline
and repeat 1,2,3,T or TC. The amounts entered are added to
the previous totals.

The program uses several subroutines for tabulation, to
persaude the ZX80 to add and subtract decimals and to
ensure that the results are printed correctly.

390 GOSUB SOOO

395 PRINT "...4"i

400 LET X * L

404 LET Y « L2

405 GOSUB 8000
425 PRINT ". . .5 f S
430 LET X * M
440 LET Y - M2
450 GOSUB SOOO
460 PRINT ". . „& H ,
465 GOSUB GOSUB 600
500 INPUT B$
505 PRINT

510 IF B* ■ M C M THEN GOTO 50

520 STOP

36 SYNC Magazine

600 FOR N = 1 TO 32

610 PRINT "-";

620 NEXT N

630 RETURN

1000 GOSUB 1040

1010 GOSUB 1050

1020 RETURN

1040 PRINT " " ;

1050 IF I + PEEK (16420) - 33 THEN RETURN

1060 IF I = THEN IF PEEK (16420) < 2 THEN

1070 GOTO 1040

2000 IF Y C 100 THEN GOTO 2040

2010 LET Y = Y - 100

2020 LET X = X + 1

2030 GOTO 2000

2040 RETURN

10 AND NOT Y

RETURN

2050

IF Y <
2055 IF Y ■:
2060 IF Y >
2065 IF NOT
2070 RETURN
5000 IF C =
5010 IF C ■
5020 IF C =
5030 IF C =

THEN PRINT X; "

-9 THEN PRINT X;".";Y*-1
-10 AND Y < THEN PRINT X
' < 10 THEN PRINT X?".";Y?

O

" ; Y?
sy*-i

5035 IF C = 3
5040 IF C = 3
5045 IF C = 4
5050 IF C = 4
5055 IF C = 5
5060 IF C = 5
5065 IF C = 6
5070 IF C = 6
5080 RETURN
6000 IF Y :=
6010 LET Y Y
6020 LET X = X
6030 GOTO 6000
6040 RETURN
6500 LET Y = Y
6510 LET X = X
6520 GOTO 90 1
7000 LET X = X
7010 LET Y = Y
7020 GOTO 9020
3000 GOSUB 9000
8100 GOSUB 2000
8020 GOSUB 2050
3030 RETURN
9000 IF Y < AND
9010 IF X > AND
9020 IF X < AND
9030 RETURN

1 THEN LET G ■ G +

1 THEN LET G2 = G2

2 THEN LET H = H +

2 THEN LET H2 = H2

3 THEN LET J = J +
3 THEN LET J2 = J2

THEN LET K ■ K +
THEN LET K2 » K2
THEN LET L - L +
THEN LET L2 = L2
THEN LET M = M +
THEN LET M2 = M2

B2

B
+
B

+ B2
B

+ B2
B
+
B

B2
62
B2

-100 THEN GOTO 6040
1 00

1 00

1

i
1 00

X
Y
Y

THEN GOSUB 6000
THEN GOTO 6500
THEN GOTO 7000

The magazine for Sinclair ZX80 users

L|n

T-SHIRTS!

Proclaim the computer of your choice on your
chest with our own Crash Cursor and Sync,
Design is silver on dark blue shirt for a striking
effect. Available in adult S,M,L and XL. $6.00
postpaid in U.S.A.; 3,00 postpaid in U.K. Send
US. orders to SYNC, 39 East Hanover Ave.,
Morris Plains, NJ 07950. Send U.K. orders to
SYNC, 27 Andrew Close, Stoke Golding,
Nuneaton CV1 3 6EL.

Jan/Feb 1981

37

Adding an LED Load Monitor to the ZX80

Cecil Bridges

The input signal level is critical when
loading a program from cassette tape.
Save and Load operations can be done
with the computer as it exists: One estab-
lishes the correct volume control setting
on the tape recorder by trial and error.
One then secures the volume control in
the correct position with sticky tape, or
makes a couple of index marks which
allow the recorder to be set properly. If
one's tape recorder batteries age, or if
one tries to load a program recorded by
someone else, then a new level has to be
re-established by trial and error.

An alternative is to use a load monitor
to show when a program to be loaded is
at the correct level. Initially, I dedicated
an oscilloscipe as a load monitor, but this
seemed like overkill, particularly in view
of the size discrepancy between the
'scope and the computer. I then added a
single LED (light emitting diode) to the
tape "ear" input of the computer. The
voltage for lighting the LED is just right
for loading a program from the cassette
tape.

In order to add the LED, it was neces-
sary to get the top off the computer. This
was no problem for me because I had
already destroyed the plastic rivets in
attempting to assemble my Microace,
and had substituted small screws. You
may want to add the Microace 2K RAM
option at a later date, and screws look
better than the rivets anyway, so very
carefully drill out the five rivets around
the outside of the top cover, taking
special care not to damage the printed
circuit board. Get out your soldering
pencil and thin rosin core solder. The
LED can be soldered into the printed
circuit board from the top if you want to

avoid taking out the rivets holding the
board to the bottom of the case. The
short lead on the LED is attached just
below the input ("ear") jack at the point
marked X in the illustration and the long
lead attaches at the point marked Y. You
will probably have to extend the leads of
the LED with fine insulated wire. Drill a
hole in the top of the case where the LED
will stick through. Use insulating tape on
the bare lead wires of the LED and
assemble the case.

To minimize any interaction with the
input circuit, use small LEDs which draw
less current and have less capacitance
than the large ones. I found mine, red,
about 2mm in diameter, at Radio Shack.
Be careful when bending the leads of
these little LEDs; any strain on them will
break their little red plastic cases.

In use, the LED will just light up when
the tape recorded program is coming in
at the correct level, and will remain dark
or barely flicker when it is too low for the
computer to accept.

I used the single LED load monitor for
a while, but later added two additional
components to make a more elegant
monitor. A second LED was added in
parallel with the first, with a silicon diode
in series with it to drop the voltage
slightly. See the wiring diagram in the
illustration. The second LED then acts as
an over-voltage indicator when it is lit.
The 3/4 volt forward conduction voltage
drop across the silicon diode makes a
fairly precise bracket for the input volt-
age. Solder the second LED and the sili-
con diode to the lead extensions of the
first LED, not to the printed circuit
board.

Setting the correct tape recorder
volume level for loading is now simple.
Given a taped program recorded at some
unknown level, the volume level is in-
creased (while the tape recorder is play-
ing back the recorded program) until the
first LED lights up and the second re-
mains dark. Rewind the tape and it
should then load successfully.

Cecil Bridges, 1248 N. Denver, Tulsa, OK 74106.
38

SYNC Magazine

New Peripherals from Sinclair

Printer

"Extremely low cost." That's the answer
I got when I asked Nigel Searle about the
forthcoming Sinclair printer. Relentlessly,
I pressed for more.

It is a line-at-a-time printer and only
prints a line when the user hits NEWLINE.
"Seems awkward," said I. "Extremely low
cost," said Nigel.

It has a 32-character line, the same as
the display. "That means non-standard
paper," said I. "Extremely low cost," said
Nigel.

The printer uses a dot matrix and prints
the complete ZX80 graphics character
set. "Very nice," said I. "Yes," agreed
Nigel.

Flat Screen Display

When I interviewed Clive Sinclair last
fall, he indicated that the major research
program at that point was flat screen
television. Nigel Searle informs us that
working prototypes have been produced
and that a factory is now being built to
produce the units. Production units are
expected by December 1981.

The CRT measures 3 inches across the
diagonal. Sinclair is currently considering
a projection device to increase the effective
picture size to 5 inches. The CRT tube is
an astonishing 3/8" thick.

A standard, but miniature, projection
gun shoots the beam parallel to the surface
of the screen and it is then bent. The
principal itself is not new, however, this is
the first time it has been successfully
executed.

Clive Sinclair was emphatic that the
company would not introduce anything
that was not price competitive with existing
technology. However, he would not
elaborate on the price of the flat screen
TV in September when we talked. Now,
with four months of additional experience
with the unit, Nigel tells us that the original
retail target price was $125 or £ 50. This
was for a broadcast TV receiver. (Existing
conventional 3" units now on the market
carry retail prices of $200 and up.) How-
ever, more good news. It appears by
employing a highly automated production
line, the original target price can be beaten
down some 40% to $75 or £ 30.

Sinclair Withdraws 8K Basic ROM

We read with interest in Computer
Weekly that Clive Sinclair has withdrawn
the 8K Basic ROM chip for the ZX-80
until the first quarter of 1981. This occurred
only a month after it was announced to
the world (September 11, 1980). He denies
rumors that software bugs are the cause
and blames the delay instead on the
incorporation of extra functions.

The 8K ROM chip is supposed to direcdy
replace the original 4K ROM even though
there is no upward compatability between
the two slightly different Basics. When it
eventually appears, the 8K ROM will enable
the ZX-80 to work in floating point
arithmetic to 9-digit accuracy.

The extra functions now being incor-
porated in the chip mainly consist of a
printer driver. The printer is planned for
introduction in the first half of 1981.

In explaining the product announcement
and subsequent withdrawl, Sinclair stated,
"We were caught out. We wanted to bring
out the 8K as soon as possible, but on the
other hand we did not want to be severely
critisized at a later stage when we would
have to bring out another version."

8K Basic ROM

Originally announced in September 1980
and then withdrawn, the 8K Basic will
probably be out by the time this is printed.

The new one differs from the original
in that it incorporates a printer driver
routine and one other new feature about
which Sinclair is being quite secretive.
Some minor functions were cut out of the
first version to make way for these two
new features.

Sinclair either doesn't know or isn't
saying whether the 8K Basic will work in
the MicroAce. Apparently there is no love
lost between the two companies even
though they have a rather close business
licensing arrangement. Reputable sources
tell us that, indeed, the 8K ROM will
work in the MicroAce.

30 Programs
for the
Sinclair ZX-80-

a Review

David Lubar

30 Programs for the Sinclair ZX-80, by

Melbourne House, Glebe Cottage, Glebe
House, Station Road, Cheddington,
Leighton Buzzard, Bedfordshire, England,
distributed in the United States by Image
Computer products, 615 Academy Drive,
Northbrook, IL 60062, 1 1 1 pages, paper-
back $14.95. 1980.

30 Programs for the Sinclair ZX 80
published by Melbourne House, contains
games and utilities that will run in IK of
memory. But the book is more than just a
collection of programs; it is a storehouse
of valuable techniques and tricks. While
many of the programs are entered in the
usual way, some are entered in ways that
expand the capabilities of the Sinclair. For
example, several of the programs come in
two parts. The first part accepts inputs
which are stored as data for the second
part. In "Lunar Lander," these data are
used to draw the rocket ship. In "Dr. ZX-
80" (see Creative Computing's More
Basic Computer Games for the original
Dr. Z), the data are used to store strings in
memory.

These techniques alone make the book
worthwhile. Add to this the fun of the
games themselves, from a simple "Leap
Frog" to the complex programming of
"Gomoku, ,, and you have a bargain that
should be a part of every Sinclair owner's
library.

The listings are presented in clear, large
type. The numbers are larger than the
letters, thus avoiding confusion be-
tween zero and the letter O, as well as
one and the letter I. Each program is
preceeded by a description which covers
any special techniques used. The only
shortcoming is the lack of sample runs. It
is always nice to see what a program does
before going to the touble to enter the
whole thing. Also, sample runs can help
show where you went wrong if there is an
error in your typing. Despite this, the
book is highly recommended.

You will find two programs from the
book reprinted in this issue of SYNC.
"Life" and "Draw a Picture" were re-
printed courtesy of Melbourne House
Publishers.

Jan/Feb 1981

39

Lin sac s Game Programs 1 and 2
A Review

Jonathan A Stein

Linsac of England is now producing
software for the Sinclair ZX-80. In addi-
tion to publishing the book, The ZX-80
Companion, they are marketing a series
of educational and game cassettes, all of
which are reaching The United States
through Image Computer Products, 615
Academy Drive, Northbrook, Illinois
60062. In the U.K. they are available di-
rectly from Linsac, 68 Barker Road,
Middlebrough TS5 5ES, England.

Although there are five games cas-
settes packages, we chose to look at the
two for the IK computer, since this is the
most common version of the machine.
We will reserve reviewing the educa-
tional cassettes and the games for the 2K
version until a later date. Games Pack
One includes Three Towers, Number
Guessing, Mastermind, Sketches,
Hurkle, Nim, and Simple Simon.

Three Towers is a version of the game
Tower of Hanoi, in which the object is to
take six graduated rings and move them
from the first of three rods to the third,
without ever placing a larger ring on top
of a smaller one. The game is difficult
until one figures out the system needed to
make it work, although it continues to be
time consuming. If, however, you make
an improper entry, the program is unfor-
giving, sometimes forcing you to begin
again.

The second game on the cassette is
Guess a Number, which has the player
deduce a number between 1 and 100
based on hints offered by the program,
which tell the player whether his or her
guess is above or below the value of the
number trying to be guessed. This game
should be particularly interesting to a
child, but for an adult it is a bit limited.

40

Mastermind is a version of the popular
board game of the same name. The ma-
chine selects a four digit code which you
try to solve. After you enter your guess,
the computer responds, letting you know
how many digits are correct and in the
right location, and how many are correct,
but improperly situated. The game is ex-
tremely challenging, and made more dif-
ficult by the way in which it treats dupli-
cated digits. For example: if the code
contains two zeros, and you only have
one in your guess, the machine will tell
you that you have one digit in the right
place and one in the wrong place.

In Sketcher, an introductory program
for computer graphics. The player is
given a 31 x 16 grid, on which he can enter
designs. As a first encounter with compu-
ter drawing, the program is very good,
and can be a delight to small children and
of interest to adults.

Linsac's version of Hurkle is a pleasure
to play. The player is given a 15 x 15 grid
in which a Hurkle is hiding. To find the
Hurkle one must pick X and Y values
corresponding to the location of the
beast. With only five guesses, you must
quickly follow the hints provided by the
computer. To keep track of your path, I
would recommend writing down both
your guesses and the computer hints.

Nim is another game on this cassette,
in which the player competes against the
computer by taking stones away from
several piles. The object is to be the last
player to take a stone. The human player
has the option to establish the number of
piles, and the number of stones in those
piles. The game is pleasant, and can often
be challenging.

Symbol Simon is the final game in this
series. The computer establishes a pat-
tern of letters, numbers, or graphics,
depending upon your selection. The
game is fairly easy, because it just entails
repeating what the program presents.

The second Linsac game package
offers several more challenging games
and exercises than does the first selection
of games. It includes Nine Lives, The
Maze Game, Plain Sailing, Noughts and
Crosses, Chinese Puzzle, Tower of
Hanoi, and Battleships,

The first game is Nine Lives, a version
of the children's game Hangman. Two
people play, using the machine as both
the paper and the scorer. The first player
enters a word, and the computer tells the
second person the number of letters in
that word by displaying a dash for each
character. With each incorrect letter
entry, one of nine lives is lost. The game
continues until the word is completed, or
until all of the lives are gone.

The Maze Game, the second game on
the tape, is one of the better Linsac games
I sampled. The object is for the player to
find his way through a constantly chang-
ing maze to a treasure. Quite often the
maze closes in to make reaching the
booty impossible. After the game ends,
either by winning the treasure, or by con-
ceding defeat (by entering 0), the compu-
ter posts the score out of a possible 18.

Plain Sailing is the third "game" on the
cassette. Actually more a mathematical
exercise than a game, it entails sailing a
dinghy, with a top speed of six knots
through a chanel four miles long and two
miles wide. The sailor selects the wind
speed and direction, as well as the tidal
force and direction. After entering this
information the player must determine
the length of time and number of tacks
needed for the journey. The computer
then posts the actual number of minutes
and tacks required. Although this is
really not a game as such, it is extremely
interesting, requiring a good deal of
thought and attention.

SYNC Magazine

The fourth game, Noughts and
Crosses, commonly known as Tick Tac
Toe, offers the player more of a chal-
lenge than one usually expects from this
game. The ZX-80 version of this old fa-
vorite requires a different kind of
strategy than when the game is played
against a human opponent, because the
machine is so consistent. For instance: If
your first move is in the center square,
the ZX-80 will always play the lower right
square. If however, you choose any
square but the center, the machine takes
the center position. The machine will
consistently win unless you take a radical
plan to keep you moves on the offensive.
Once you are forced into a defensive
position, the machine will win, or you will
draw.

The next game, Chinese Puzzle, is a
challenging game requiring a great
amount of patience. The object is to slide
the alphabet squares around until they
are in proper order. Considering there is
just one vacant place on the board, this
becomes a major task. The game easily
becomes frustrating, because it seems
that you can never really gain ground,
you just switch around the squares which
are in the proper positions. The game is
fairly good if you are long on patience
and endurance.

Tower of Hanoi is virtually identical to
the Three Towers game already re-
viewed in this article. The primary differ-
ences are the way in which the entries are
made, and that in this game the game is
won by setting up all of the rings on
either the second or third rod, rather
than just on the third column as in the
Three Towers game. The game is
moderately challenging, but one version
is enough.

The final game on the cassette is
Battleships, which is basically a compu-
terized version of the old board game
Battleship, in which the object is to sink
the enemy ships on a grid marked with X
and Y coordinates. The main difference
between the ZX-80 version and the board
version is that the player does not have a
fleet of his own. This game is based
totally on trial and error, as one ran-
domly picks X and Y coordinates to fire
torpedoes into the enemy waters. The
game easily becomes tiresome, because it
requires no skill or cunning, just the
methodical entering of coordinates.

Both of the Linsac tape packages offer
some intersting games and exercises, of
which my favorites are: Hurkle, The
Maze Game, Plain Sailing, and one of the
Tower games. Most of the games are
made a little eaiser if you use pencil and
paper to record your moves. The games
packages are definately worth having al-
though several of the games are not
terribly challenging.

Jan/Feb 1981

' Sourcebook
off Ideas

Many mathematics ideas can be better illustrated
with a computer than with a text book.

Computers

Creative Computing Press

Consider Baseball cards. If there are 50
cards in a set, how many packs of bubble
gum must be purchased to obtain a complete
set of players? Many students will guess
over 1 million packs yet on average it's only
329.

The formula to solve this problem is not
easy, The computer simulation is. Yet you
as a teacher probably don't have time to
devise programs to illustrate concepts like
this.

Between grades 1 and 12 there are 142
mathematical concepts in which the com-
puter can play an important role. Things
like arithmetic practice, X-Y coordinates,
proving geometic theorems, probability,
compounding and computation of pi by
inscribed polygons.

Endorsed by NCTM

The National Council of Teachers of
Mathematics has strongly endorsed the use
of computers in the classroom. Unfortunately
most textbooks have not yet responded to
this endorsement and do not include pro-
grams or computer teaching techniques.
You probably don't have the time to develop
all these ideas either. What to do?

For the past six years, Creative Computing
magazine has been running two or three
articles per issue written by math teachers.
These are classroom proven, tested ideas
complete with flowcharts, programs and
sample runs.

Teachers have been ordering back issues
with those applications for years. However,

many of these issues are now sold out or in
very short supply.

So we took the most popular 1 34 articles
and applications and reprinted them in a
giant 224-page book called Computers in
Mathematics: A Sourcebook of Ideas.

Ready-to-use-material

This book contains pragmatic, ready to
use, classroom tested ideas on everything
from simply binary counting to advanced
techniques like multiple regression analysis
and differential equations.

The book includes many activities that
don't require a computer. And if you re
considering expanding your computer
facilities, you'll find a section on how to
select a computer complete with an invalu-
able microcomputer comparison chart.

Another section presents over 250
problems, puzzles, and programming ideas,
more than are found in most "problem collec-
tion' books.

Computers in Mathematics: A Sourcebook
of Ideas is edited by David Ahl, one of the
pioneers in computer education and the
founder of Creative Computing.

The book is not cheap. It costs $15.95.
However if you were to order just half of the
back issues from which articles were drawn,
they would cost you over $30.

Satisfaction Guaranteed

If you are teaching mathematics in any
grade between 1 and 12, were convinced
you'll find this book of tremendous value. If,
after receiving it and using it for 30 days
you do not agree, you may return it for a full
refund plus your return postage.

To order, send your check for $15,95
plus $1 .00 postage and handling to Creative
Computing Press, Morris Plains, NJ 07950
Visa, MasterCard, and American Express
orders may be called in toll-free to 800-
631-8112 {in NJ 201-540-0445). School
purchase orders should add an additional
$1 .00 billing fee for a total of $1 7.95.

Don t put it off. Order this valuable source-
book today.

creative
computing

Morris Plains, NJ 07950
Toll-free 800-631-8112

(InNJ 201-540-0445)

41

Resources for the ZX-80
and MicroAce

Presented below is a list of currently available
products related to the Sinclair ZX-80. Such a list
can never be complete, of course. We intend to
run this as an ongoing column and in addition,
we intend to expand the entries to include a
description of each product. In this and other
issues you will find in-depth evaluations and reviews
of many of these products.

We welcome entries from manufacturers and
readers for the resources column. Please include
the name of the item, a brief description, price,
and complete data on how to obtain it. Send
contributions to SYNC Resources, 39 East Hanover
Avenue, Morris Plains, New Jersey 07950.

Computers

Sinclair ZX-80 (Great Britain):
IK assembled - £ 100.00
IK kit without power source — £ 80.00

Science of Cambridge
6 Kings Parade
Cambridge, Cambs CB2 1SN
England

Sinclair ZX-80 (United States):
IK assembled - $200.00

Sinclair Research Limited
50 Stamford Street
Boston, MA 021 14

MicroAce Computer:
IK kit - $149.00
2Kkit -$169.00

MicroAce

1348 East Edinger

Santa Ana, CA 92075

Hardware

Plug in RAM chips for the ZX-80.
IK - £ 20, 2K - £ 30, 3K - £ 40

Quicksilva

56 Bedford Place

South Hampton, Hants

England

Software and Books

Games and technical information for the Sinclair
ZX-80.

Bobker

29 Chedderton Drive

Unsworth, Bury, Lanes

England

Four cassette tapes — £ 3 each:

1. Moon-landing, Hangman, Code breaker, Inter-
cept

2. Bio-rhythm, Solitaire, Battleship, Dice

3. Bingo, Minefield, Remcard, Sequences

4. Five Mathematics Programs

Bug-Byte

251 Henley Road

Coventry CV2 1BX

England

IK Games for the ZX-80:

Mastermind, Hangman, Simon, Computamath —

£ 2 each, four for £ 5.50 incl.

4K Element Math Package - £ 7.50 incl.

Bush Green Enterprises Limited

80 Dumont Avenue

Point Clear, Essex CO 16 8JR

England

ZX-80 Software (games and educational):
Dicethrow, Mastermind, DIV Package, Electro
Bandit, Math Programs, and Word Puzzles —
£ 5.00 each, three for £ 12.00

CDS Micro Systems

10 Westfield Close, Tickhill

DoncasterDN 119LA

England

Software on cassette for IK ZX-80:
Simon, Mind Bender, Destroyer, Fruit Machine
— £ 5.00, and a general mathematics program
for £ 5.00

Econo Soft

4 The Loont

Winsford Cheshire CW 7 1EU

England

Software for the ZX-80

Tim Hartnell

44-46 Earls Court Road

London W8

England

42

SYNC Magazine

Software Cont.

ZX-80 game for 1 or 2 players - £ 1.50 in UK

R. Hindle

139 Penrhyn Road

Sheffield, SI 18UP

England

Offers an extensive line of ZX-80 Software.
Includes Computer Learning Lab book and tape
package — $49.95, a wide selection of game
programs, as well as Software produced by Linsac,
Melbourne House, and Creative Computing.

Image Computer Products
615 Academy Drive
Northbrook, IL 60062

Games package for IK ZX-80:

K Treck, Life, Mind Master, Lunar Lander, four

for $9.95, and an Introductory tape for $2.99

Lamo-Lem

712 Pidgeon Street

San Diego, CA 921 14

The ZX-80 Companion — $19.95, and nine
programmed cassettes, of both educational material
and games — $6.95 each.

Linsac

68 Barker Road

Middlebrough TS5 5ES

England

ZX-80 Active Display - £ 5.00, and software.

K. Macdonald
26 Spiers Close
Knowle, Solihull B93 9ES
England

ZX-80 Magic Book
and I/O boards

£ 4.75, and ZX-80 memory

£ 7.45 in the UK,

30 Programs for the ZX-80
£ 7.95 outside the UK

Melbourne House Publishers
Glebe Cottage, Glebe House
Station Road, Cheddington
Leigh ton Buzzard, Bedfordshire
England

Software Packages for the ZX-80

The Software House
146 Oxford Street
London Wl
England

Games for the ZX-80, three cassette packages
£ 4.95 each

Syntax Software

96 Collingwood Gardens

Giants Hill

Ilford, Essex

England

Timedata Limited
57 Swallowdale
Basildon, Essex
England

ZX-80 Teaching Aids:

2X to 10X times tables on cassette - £ 5.00

Higher level teaching programs - £ 5.00

Turner Consultants

Falconsbeck

Holbeck Lane, Windmere, Cumbria

England

20 ZX-80 Programs, a book for £ 5.25
cassette and book for £ 1 1.00

Zipprint

1 1 Romsey Road

Winchester, Hants

England

Users Groups and Newsletters

Publishes Syntax ZX-80

12 month subscription — $25.00 in The United

States, $39.00 in Western Europe, and $30.00 in

Canada.

The Harvard Group

RD 2 Box 457
Bolton Road
Harvard, MA 01451

Bi-monthly newsletter, low cost software, sub-
scription - £ 6.00 in UK, £ 10.00 overseas

ZX-80 User's Club

c/o D. Blagden

P.O. Box 159

Kingston Upon Thames, Surrey

KT2 5UQ

England

Seeks to create and share software for the IK
ZX-80. Membership is free (enclose postage).
Publishes the newsletter, Interface.

ZX-80 User's Club
c/0 Tim Hartnell
93 Coningham Road
London W12
England

SYNC cannot vouch for any of the
sources listed above. We welcome objec-
tive, in-depth reviews of any of these
items and others related to the ZX80.

Jan/Feb 1981

43

The Sinclair ZX80 is innovative and powerful.
Now there's a magazine to help you get
the most out of it.

Get in
sync

SYNC magazine is different from other
personal computing magazines. Not just
different because it is about a unique
computer, the Sinclair ZX80 (and kit ver-
sion, the MicroAce). But different be-
cause of the creative and innovative phi-
losophy of the editors.

A Fascinating Computer

The ZX80 doesn t have memory map-
ped video. Thus the screen goes blank
when a key is pressed To some review-
ers this is a disadvantage. To our editors
this is a challenge. One suggested that
games could be written to take advan-
tage of the screen blanking. For exam-
ple, how about a game where characters
and graphic symbols move around the
screen while it is blanked? The object
would be to crack the secret code gov-
erning the movements. Voila! A new
game like Mastermind or Black Box
uniquely for the ZX80.

We made some interesting discoveries
soon after setting up the machine. For
instance, the CHR$ function is not limit-
ed to a value between and 255, but
cycles repeatedly through the code
CHR$ (9) and CHR$(265) will produce
identical values. In other words, CHR$
operates in a MOD 256 fashion. We
found that the "- " sign can be used se-
veral times on a single line, allowing the
logical evaluation of variables. In the
Sinclair, LET X=Y=Z=W is a valid ex-
pression.

Or consider the TL$ function which
strips a string of its initial character. At
first, we wondered what practical value it
had. Then someone suggested it would
be perfect for removing the dollar sign
from numerical inputs.

Breakthroughs? Hardly But indicative
of the hints and kinds you'll find in every
issue of SYNC. We intend to take the
Sinclair to its limits and then push be-
yond, finding new tricks and tips, new
applications, new ways to do what
couldn t be done before. SYNC functions
on many levels, with tutorials for the be-
ginner and concepts that will keep the
pros coming back for more. We II show
you how to duplicate commands avail-
able in other Basics. And, perhaps, how

to do things that can't be done on other
machines.

Many computer applications require
that data be sorted But did you realize
there are over ten fundamentally differ-
ent sorting algorithms? Many people
settle for a simple bubble sort perhaps
because it s described in so many pro-
gramming manuals or because they've
seen it in another program. However,
sort routines such as heapsort or Shelt-
Metzner are over 100 times as fast as a
bubble sort and may actually use less
memory. Sure, 1 K of memory isn't a lot
to work with, but it can be stretched
much further by using innovative, clever
coding. You'll find this type of help in
SYNC

Lots of Games and Applications

Applications and software are the meat
of SYNC. We recognize that along with
useful, pragmatic applications, like finan-
cial analysis and graphing, you'll want
games that are fun and challenging. In
the charter issue of SYNC you'll find se-
veral games. Acey Ducey is a card game
in which the dealer (the computer) deals
two cards face up. You then have an op-
tion to bet depending upon whether you
feel the next card dealt will have a value
between the first two.

In Hurkle, another game in the charter
issue, you have to find a happy little
Hurkle who is hiding on a 10 X 10 grid. In
response to your guesses, the Hurkle
sends our a clue telling you in which
direction to look next.

One of the most ancient forms of arith-
metical puzzle is called a "boomerang. '
The oldest recorded example is that set
down by Nicomachus in his Arithmetica
around 100 AD. You'll find a computer
version of this puzzle in SYNC.

Hard-Hitting. Objective Evaluations

By selecting the ZX80 or MicroAce as
your personal computer you've shown
that you are an astute buyer looking for
good performance, an innovative design
and economical price However, select-
ing software will not be easy That's
where SYNC comes in SYNC evaluates
software packages and other peripherals

and doesn't just publish manufacturer
descriptions. We put each package
through its paces and give you an in-
depth, objective report of its strengths
and weaknesses

SYNC is a Creative Computing pub-
lication. Creative Computing is the num-
ber 1 magazine of software and applica-
tions with nearly 100,000 circulation.
The two most popular computer games
books in the world, Basic Computer
Games and More Basic Computer
Games (combined sales over 500,000)
are published by Creative Computing.
Creative Computing Software manufac-
tures over 1 50 software packages for six
different personal computers

Creative Computing, founded in 1974
by David Ahl, is a well-established firm
committed to the future of personal com-
puting. We expect the Sinclair ZX80 to
be a highly successful computer and
correspondingly, SYNC to be a respect-
ed and successful magazine.

Order SYNC Today

To order your subscription to SYNC, in
the USA send $10 for one year (6
issues), $18 for two years (12 issues) or
$24 for three years (18 issues). Send
order and payment to the address below
or call MasterCard, Visa or American Ex-
press orders to our toll-free number.

Subscriptions in the UK are mailed by
air and cost £ 10 for one year, £ 18 for
two years or £ 25 for three years. Send
order and payment to the UK address
below.

Canadian and other foreign surface
subscriptions cost $15 per year or $27
for two years and should be sent to the
USA address.

We guarantee your satisfaction or we
will refund your entire subscription price.

Needless to say, we can't fill up all the
pages without your help. So send in your
programs, articles, hints and tips.
Remember, illustrations and screen
photos make a piece much more inter-
esting. Send in your reviews of peripher-
als and software too— but be warned: re-
views must be in-depth and objective.
We want you to respect what you read on
the pages of SYNC so be honest and
forthright in the material you send us. Of
course we pay for contributions— just
don't expect to retire on it.

The exploration has begun. Join us

The magazine for Sinclair ZX80 users

39 East Hanover Avenue

Morris Plains, NJ 07950, USA

Toll free 800-631-8112

(InNJ 201-540-0445)

27 Andrew Close, Stoke Golding
Nuneaton CV13 6EL, England

SYNC Reader Survey

We at SYNC would like to know more about you. That way, we can determine what kinds of material to run in the
magazine that will best meet your needs.

In Sync, I would like to see:

very much

okay

forget it

Hardware Tutorials

□

m

D

Software Tutorials

■

D

D

Games

■

□

D

Simulations

■

□

□

Educational Software

a

■

□

Mathematics Software

a

a

D

Graphics Software

m

□

□

Business Software

D

□

41

Device Control Software

m

□

a

Programming Tips

m

a

□

Interfacing Techniques

m

a

□

New Products Information

m

□

a

Hardware Evaluations

■

a

a

Software Evaluations

m

□

□

Fiction

D

□

m

Puzzles and Problems

□

a

m

Advertising

■

□

D

About Software:

■ I like to mainly write my own

□ I mainly use software from other sources

□ A bit of both

Is the ZX 80 or MicroAce your only computer?

• Yes

□ No, I also have a

I utilize a computer at (check all that apply)

□ Work ■ Home

□ School □ Other

Which of the following peripherals do you intend to purchase for
your ZX80 (assuming they become available)?

V Additional memory

jB Floppy Disk

Small Printer

□ Letter Quality Printer

□ Graphics Tablet

□ Modem

□ Music Synthesizer

□ Other

What other computer magazines do you regularly read?

Age:

M Under 20

□ 21-30

□ 31-40

Sex: Male

□ 41-50

□ 51-60

□ Over 60

□ Female

What was the main reason you bought a ZX 80 or MicroAce?

-^7

Comments: &-ij* And circuit, ^^ ^v^v-y -

jrh^j^Ki^r^ JCa.

^•g-^^evc^g-

t^V yyr^cir^C^

;^7 ftX ^

Name /j n ^ € ^ /f^ „ ^^y

Address

g CclUmT Ave.

TKcf^s '?p^. 0/&.06

Return to SYNC, 39 East Hanover Avenue, Morris Plains, N.J. 07950

Are you in SYNC?

If not, you should be. We would like any
programs, translations of existing pro-
grams, games or tips which you have to
pass on to fellow Sinclair ZX-80 or Micro-
Ace owners. Articles are much more
lively if accompained by photos (black
and white), diagrams, and illustrations. If
you do not have an output printer, please
type program listings and carefully check
them against the listing on the screen.

Jan/Feb 1981

Sample runs should be included with pro-
grams rather than just a description of
what the program does. Articles should be
typed, double space. Your name and
address, with phone number should be on
first page; all other pages should be num-
bered. All submissions should include re-
turn postage. Payment ranges from $15 to
$40 per printed page.

Please send all submissions to:
SYNC

39 E. Hanover Avenue
Morris Plains, New Jersey 07950

Find ZX-80
Owners

Advertise in SYNC, the magazine ex-
clusively dedicated to the Sinclair ZX-80
and The MicroAce. Call or write for de-
tails and a rate card. Let SYNC readers
know who you are.

SYNC

39 E. Hanover Ave.

Morris Plains, New Jersey 07950

45

Glossary of Computer Terms

Access Time

The interval of time between the calling
for information from a storage address
and the delivery of that information. In
general, tape has a longer access time
than disk.

Address

A label (name or number) that desig-
nates a location where information is
stored in memory device.

Alphanumeric

A set of symbols. Can be letters (A-Z),
and/or special punctuation, mathmatical,
or graphic symbols.

Architecture

The internal, preset arrangement or
organization of a computer which deter-
mines how the computer operates. The
interconnections of registers, logic units,
control logic, etc. that which makes one
microprocessor different from another.

Basic

An acronym for Beginners All Purpose
Symbolic Instruction Code. A high-level
conversational, interpretive, program-
ming language in wide use. Basic was in-
vented by Kerne ny and Kurtz at
Dartmouth college in 1963. It permits the
use of simple English words and common
mathmatical symbols to perform the nec-
essary arithmetic and logical operations
to solve problems.

Bit

The smallest amount of information
that can exist: equivalent to yes/no,
on/off, +/-, or 0/1.

Byte

A collection of bits, usually eight of
them.

Code

The relationship between bits and a set
of characters. Microcomputers deal only
with bits when executing a program.
Therefore, letters, numbers, and other
human understandable characters must
be translated into bits. Each character has
a bit code representation.

Coding

Preparing a set of computer instruc-
tions.

Command

An instruction given to the system
through an input device or peripheral. It is
executed as soon as it has been received.

Compatibility

There are two types of compatibility:
Program and hardware. Program compat-
ibility refers to the ability to run programs
on a variety of computers without change
the program language. Hardware compat-
ibility means that various components
(printers, disks, keyboards, etc.) may be
connected directly without intervening
electronic devices.

Console

The operating portion of a unit.

Courseware

A combination of content, instructional
design, and the software which causes a
computer to implement instructions.

CPS

Cycles Per Second

CPU

Central processing unit. The heart of
the computer, controlling what the com-
puter does. It includes three main sec-
tions: arithmetic, control, and logic ele-
ments. It performs computations and di-
rects functions of the system.

Creative Computing

The second best source of Sinclair ZX-
80 information.

Crunch

To make information fit into a smaller
place.

CRT

Acronym for Cathode Ray Tube. Simi-
lar in appearance to a television screen.
Information in the form of characters and
graphic designs may be displayed on
CRTs at a rapid rate. A CRT terminal
usually comes with a keyboard for enter-
ing information into the computer.

Cursor

Movable indicator on CRT to indicate
a specific character or space that is being
displayed. The cursor generally lets the
user know where the next character to be
typed will appear.

Data

The information given to or received
from a computer.

Debug

Process of finding, locating, and cor-
recting mistakes or errors in a program
that might create problems or provide in-
accurate information.

Digit

Either a zero or a one in the binary
number system.

Direct Memory Access (DMA)

A technique for rapidly moving data
from the microprocessor to a storage de-
vice such as a disk. DMA is a accom-
plished at the direction of a program. Not
all microcomputers permit DMA.

46

SYNC Magazine

Document

A written description of a piece of soft-
ware or hardware. It can also be used as a
verb which is the process of producing
such a description.

Driver

Small program which controls periph-
eral devices and their interface with the
CPU.

Editor

A program which allows changing,
modification, or movement of program-
ming statements. It allows the pro-
grammer to write and modify instructions
using the microprocessor and a terminal
as a very sophisticated typewriter.

Error

Difference in value between actual re-
sponse and desired response in the per-
formance of a controlled machine,
system, or process.

Execute

The running of a computer program.

External Storage

Auxiliary storage such as tape or disk.

File

Collection of related data.
File Name

Number/letter of characters that iden-
tify a file.

Flow Charting

A programming technique of using
shaped blocks to indicate the sequence of
operations in a program.

Frequency

Rate at which anything recurs.

GIGO

Garbage in Garbage Out. Implies that
misinformation applied to the CPU will
result in misinformation output.

Glitch

An intermittent bug

Graphics

Characters that can be used to form
figures, shapes, and forms on the CRT or
printer. In addition to letters and num-
bers, a computer may have a graphic set,
so arrange that they can be combined to
form almost any desired figure.

Hard Copy

Data or information printed on paper.
Used to distinguish between printed infor-
mation and the temporary image found on
the CRT.

Hardware

Mechanical, magnetic, electrical, and
electronic devices which make up a com-
puter. The physical equipment that goes
into a computer system, consisting of the
central processing unit plus all periph-
erals.

IC

Integrated Circuit. A plastic or ceramic
body five cm long, two cm wide, and three
mm thick, with up to 40 leads extending
from it. Inside the body is a chip. The
body protects the chip, and the leads
allow electrical connection of the chip to
other components. The word "chip" is not
used to refer to the entire IC.

Input

Information going into the computer or
into a peripheral. The same data may be
output from one part of the computer and
input to some other part of the computer.
When using this word, specify what the
data are input to or output from.

Instruction

A set of bits, or a command, which will
cause a computer to perform certain pre-
scribed operations.

Interactive

System capable of two-way communi-
cations with a user during operation. A
system is interactive if it responds to the
user quickly — usually less than a second.
All personal computer systems are inter-
active.

Interface

An electronic circuit used to connect
one electrical device to another electrical
or mechanical device to allow the flow of
data between units. It refers to the match-
ing or interconnecting of systems or de-
vices having different functions.

Internal Storage

Memory system which is part of the
computer, as opposed to external tape or
disk storage.

Interpreter

A program used to translate languages
at the time of processing.

I/O

Input/output of information in a com-
puter system. Examples of I/O devices are
a keyboard, a floppy disk drive, and a
printer.

Language

A format by which a programmer can
communicate more efficiently with a
computer where predetermined com-
mands will yield requested actions. Basic
is one of the most popular languages.

Low Resolution

Graphics composed of coarse blocks.

Macro-instruction

An instruction which causes the com-
puter to execute one or more other in-
structions. These "other instructions" are
called micro-instructions.

Main Memory

That memory which is directly accessi-
ble to the computer. It contains the oper-
ating system, programs, and data being
processed. In a microcomputer, main
memory is referred to as RAM or ROM.

Memory

The integrated circuits of a computer
which store information in a micro-
computer, these are referred to as RAM
and ROM.

Memory Chip

A chip which stores data in the form of
electrical charges.

Microprocessor

An integrated circuit that can execute
instructions. It is one component of a
microcomputer. It is the brains of the cen-
tral processing unit (CPU).

Jan/Feb 1981

47

Microcomputer

Printer

Run

A hardware configuration usually ac-
quired in one of three ways: 1) by con-
structing several components from indi-
vidual electronic parts (as in building a
stereo system from a kit); 2) by connect-
ing several already constructed compo-
nents (as in purchasing a separate
amplifier, speaker and turntable); or 3) by
purchasing a unit with built in compo-
nents (as in buying a complete stereo
system in one package, plugging it in, and
using it immediately). The end-product of
the microcomputer is information. It re-
cords this information, puts it into mean-
ingful terms, communicates it, stores it,
and retrieves it when needed. It usually
includes the microprocessing unit, a key-
board for entering data, and a cassette
tape recorder or a disk for storing pro-
grams, and a T.V.-like screen for display-
ing results.

Modulator

An electronic device that allows a nor-
mal television set to be used as the video
display unit (CPU).

Monitor

1) A video display unit which uses a
cathode ray tube to generate characters.
It looks much like a normal TV set; how-
ever, the monitor has a much higher de-
gree of resolution, which permits a clear
formation of very small characters on the
screen.

2) A program which oversees the opera-
tion of other programs.

Noise

Refers to inaccurate data transmission.
This causes typographical errors in out-
put.

Output

Information emanating from a display
unit such as a CRT or printer.

Peripheral Device

A device, such as a printer, mass stor-
age unit, or keyboard, which is an acces-
sory to a microprocessor and which trans-
fers information to and from the micro-
processor.

Personal Computer

A microcomputer designed for use by
an individual for entertainment, instruc-
tion, and book keeping chores.

A peripheral device which accepts out-
put data from the microprocessor and
prints characters on paper. Printers are
defined as impact or non-impact depend-
ing on the means by which a character is
formed on the paper. Impact printers
strike the paper through a ribbon in a
manner similar to a typewriter. Non-
impact printers form characters by vari-
ous means such as heat, electrical
charges, or spraying ink.

Program

A series of instructions to a computer
which cause the computer to solve a prob-
lem or perform a task.

RAM

An acronym for Random Access Mem-
ory. Any memory which can be written on
or read from by a program in which the
memory locations can be accessed in ran-
dom sequence. RAM can be erased and
reprogrammed by the programmer as fre-
quently as necessary. RAM size is ex-
pressed as a quantity of bytes, such as 4K
(4,000 bytes). RAM may be expaned by
adding memory chips or memory boards.

Register

A temporary storage device located in
the microprocessor which can hold com-
puter bits or words.

Response Time

The interval of time required for the
microprocessor to respond to an instruc-
tion or an input from a peripheral such as
the keyboard. In an educational environ-
ment, the time interval from the activa-
tion of the keyboard to a display on the
CRT should be less than three seconds.

RF Modulator

See Modulator

<S^?

Jargon for execute, (There is a run key
on the ZX-80).

Software

Refers to programs and accompanying
documentation. Software is stored on
tape cassettes or disks when not being
used by the computer. The computer
reads the software into its memory in
order to use the programs.

Storage Capacity

The quantity of bytes a storage device
can hold. It is usually expressed in kilo-
bytes (1024 bytes), which is abbreviated
K. Thus, a disk is said to have a storage
capacity of 400K (400,000 bytes). This can
be understood as 400,000 characters or
letters, numbers, spaces, etc.

Storage device

A peripheral device which holds infor-
mation. This includes tapes and disks.

Store

This term refers to the process of plac-
ing data onto some type of storage device.
Usually the data are to be kept perma-
nently; therefore, they are placed in a
non-volatile memory such as a tape, disk,
or static memory.

SYNC

To Sinclair ZX-80 owners as the Koran
is to Moslems.

Terminal

A peripheral device which facilitates
human communications with a computer.
Usually it consist of a keyboard with
alphabetic and numeric characters cou-
pled with a printing mechanism or a CRT.
One enters information via the keyboard:
the computer responds via the printer or
CRT.

Video Display Unit

A component of a microcomputer
system which displays the output on a
screen similar to a TV screen. A television
monitor is a type of video display unit.

Many of the definitions are courtesy of
Shirley Douglas and Gary Neigh ts, The
Pennsylvania Department of Education
33 Market Street, Harrisburg, PA 17126.

'Back up. what back up?*

48

SYNC Magazine

A REMARKABLE MAGAZINE

creative
GompatiRg

"The beat covered by Creative Computing
is one of the most important, explosive and
fast-changing. "—Alvin Toffler

David Ahf, Founder and
Publisher of Creative Computing

You might think the term "creative com-
puting' is a contradiction. How can some-
thing as precise and logical as electronic
computing possibly be creative? We think
it can be. Consider the way computers are
being used to create special effects in
movies— image generation, coloring and
computer-driven cameras and props. Or an
electronic "sketchpad" for your home
computer that adds animation, coloring
and shading at your direction. How about a
computer simulation of an invasion of killer
bees with you trying to find a way of keep-
ing them under control?

Beyond Our Dreams

Computers are not creative per se. But
the way in which they are used can be
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ago when Creative Computing magazine
first billed itself as The number 1 maga-
zine of computer applications and soft-
ware," we had no idea how far that idea
would take us. Today, these applications
are becoming so broad, so all-
encompassing that the computer field will
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In light of this generality, we take "appli-
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ers or might be done with computers That
is the meat of Creative Computing.

Alvin Toffler, author of Future Shock and
The Third Wave says, "I read Creative Com-
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to make the most of my own equipment but
to keep an eye on how the whole field is
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Creative Computing, the company as
well as the magazine, is uniquely light-
hearted but also seriously interested in all
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zine of software, graphics, games and sim-
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year old or a Cobol programmer can under-
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simulations, control of household devices,
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Understandable Yet Challenging

As the premier magazine for beginners, it
is our solemn responsibility to make what
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providing the reader who has no prepar-
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However, we don't want the experts in
our audience to be bored So we try to
publish articles of interest to beginners and
experts at the same time. Ideally, we would
like every piece to have instructional or
informative content— and some depth —
even when communicated humorously or
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acessible to the beginner, theoretically
non-trivial, interesting on more than one
level, and perhaps even humorous.

David Gerrold of Star Trek fame says,
"Creative Computing with its unpreten-
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the computer user to have fun. Creative
Computing makes it possible for me to
learn basic programming skills and use the
computer better than any other source.

Hard-hitting Evaluations

At Creative Computing we obtain new
computer systems, peripherals, and soft-
ware as soon as they are announced. We
put them through their paces in our Soft-
ware Development Center and also in the
environment for which they are intended-
home, business, laboratory, or school

Our evaluations are unbiased and accur-
ate We compared word processing printers
and found two losers among highly pro-
moted makes. Conversely, we found one
computer had far more than its advertised
capability. Of 16 educational packages,
only seven offered solid learning value.

When we say unbiased reviews we mean

it. More than once, our honesty has cost us
an advertiser— temporarily. But we feel
that our first obligation is to our readers and
that editorial excellence and integrity are
our highest goals.

Karl Zinn at the University of Michigan
feels we are meeting these goals when he
writes. "Creative Computing consistently
provides value in articles, product reviews
and systems comparisons ... in a magazine
that is fun to read "

Order Today

To order your subscription to Creative
Computing send payment to the appropri-
ate address below. Customers in the
continental U.S. may call toll-free to
charge a subscription to Visa, MasterCard
or American Express

Canada and
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We guarantee your satisfaction or we
will refund your entire subscription price.

Join over 80,000 subscribers like Ann
Lewin, Director of the Capital Children's
Museum who says, "I am very much im-
pressed with Creative Computing. It is
helping to demystify the computer. Its arti-
cles are helpful, humorous and humane.
The world needs Creative Computng ."

creative

Attn: Cindy

P O Box 789-M

Momstown, NJ 07960

Toll-free 800-631 -81 12

(In NJ 201-540-0445)

27 Andrew Close, Stoke Golding
Nuneaton CV13 6EL, England

Abb M ^| Licenced by Sinclair Research Ltd.

Microcomputer

for everyone at
a Micro Price

The LMkrofkeJ
I

The unique

and valuable

components of the Micro Ace

The MicroAce is not just another personal
computer. Quite apart from its exceptionally low
price, the MicroAce has two uniquely advanced
components: the powerful BASIC interpreter, and
the simple teach yourself BASIC manual.

The unique versatile BASIC interpreter offers
remarkable programming advantages:

• ^ Unique 'one-touch' key word entry: the

.MicroAce eliminates a great deal of
tiresome typing. Key words (RUN, PRINT,
LIST, etc J have their own single-key entry.

• Unique syntax check. Only lines with correct
syntax are accepted into programs. A cursor
identifies errors immediately. This prevents
entry of long and complicated programs with
faults only discovered when you try to run
them.

• Excellent string-handling capability — takes up
to 26 string variables of any length. All strings
can undergo all relational tests (e.g.
comparison). The MicroAce also has string
input — to request a line of text when
necessary. Strings do not need to be
dimensioned.

• Up to 26 single dimension arrays.

• FOR /NEXT loops nested up 26.

• Variable names of any length.

• BASIC language also handles full Boolean
arithmetic, conditional expressions, etc.

• Exceptionally powerful edit facilities, allows
modification of existing program lines.

• Randomise function, useful for games and
secret codes, as well as more serious
applications

• Timer under program control.

PEEK and POKE enable entry of machine code
instructions, USR causes jump to a user's
machine language sub-routine.

• High-resolution graphics with 22 standard
graphic symbols.

• All characters printable in reverse under
program control.

• Lines of unlimited length.

'Excellent value' indeed!

For just $149. OX) (excluding handling charge) you
get everything you need to build a personal
computer at home... PCB, with IC sockets for all
ICs; case; leads for direct connection to a cassette
recorder and television (black and white or color);
everything!

Yet the MicroAce really is a complete, powerful,
full-facility computer, matching or surpassing other
personal computers at several times the price.

The MicroAce is programmed in BASIC, and you
can use it to do quite literally anything, from playing
chess to managing a business.

The MicroAce is pleasantly straightforward to
assemble, using a fine-tipped soldering iron, it
immediately proves what a good job you've done:
connect it to your TV ... link it to the mains adaptor
... and you're ready to go.

Fewer chips, compact design,
volume production-more power
per Dollar!

The MicroAce owes its remarkable low price to its
remarkable desigh: the whole system is packed on
to fewer, newer, more powerful and advanced LSI
chips. A single SUPER ROM, for instance, contains
the BASiC interpreter, the character set, operating
system, and monitor. And the MicroAce IK byte

- a new generation of
miniature computers

A COMPLETE COMPUTER
for $149.00 for 1K Kit

Post and Packing FREE

(Add 6% Tax for Shipments inside California)

RAM (expandable to 2K on board) is roughly
equivalent to 4K bytes in a conventional computer
— typically storing 100 lines of BASIC. (Key words
occupy only a single byte.)

The display shows 32 character? by 24 lines.

And Benchmark tests show that the MicroAce is
faster than all other personal computers.

No other personal computer offers this unique
combination of high capability and low price.

The MicroAce teach-yourself
BASIC manual.

If the features of the BASIC interpreter mean
little to you-don't worry. They're all explained in the
specially-written book free with every kit! The book
makes learning easy, exciting and enjoyable, and
represents a complete course in BASIC
programming-from first principles to complex
programs. (Available separately-purchase price
refunded if you buy a MicroAce later.)
A hardware manual is also included with every kit.

The MicroAce Kit:

$149.00 with IK COMPLETE

$169.00 with 2K

Demand for the MicroAce is very high: use the
coupon to order today for the earliest possible
delivery. All orders will be despatched in strict
rotation. If you are unsuccessful in constructing
your kit, we will repair it for a fee of $20.00, post and
packing FREE. Of course, you may return your
MicroAce as received within 14 days for a full
refund. We want you to be satisfied beyond all
doubt - and we have no doubt that you will be.

Z80 A microprocessor
chip, widely recognised
as the best ever made.

Your MicroAce kit
contains...

• Printed circuit board, with
IC sockets for all ICs.

• Complete components set,
including all ICs all
manufactured by selected
world-leading suppliers.

• New rugged keyboard,
touch-sensitive, wipe-clean.

• Ready-moulded case.

• Leads and plugs for
connection to domestic TV
and cassette recorder.
(Programs can be SAVEd
and LOADed on to a
portable cassette recorder.)

• Mains adaptor of 600 mA
at 9VDC nominal
unregulated.

• FREE course in BASIC
programming and user
manual.

JOIN THE REVOLUTION - DON T GET LEFT
BEHIND - ORDER YOUR MICROACE NOW!!

I Send Check, Money Order or quote your Credit Card No. to:

' MicroAce 1348 East Edinger, Santa Ana, California, Zip Code 92705.

I or phone (714) 547 2526 quoting your Credit Card Number

Quantity

Description

MicroAce Kit 1K

$149.00

MicroAce Kit 2K

$169 00

Manual

$10.00

1K Upgrade Kit

$29.00

Shipmen
add 6%

ts inside California
TAX

TOTAL

F

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Check

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